Well, first off music is an art, much like everything else that goes into a game. Whatever you come up with and if it's what YOU want, then that's really all that matters. If you go into any kind of creative field thinking it's to please the minds of anyone but your own, then you'll end up with overly processed garbage that floods the mainstream of today, and really will not be coming up with anything original.

Music is pretty funny in a way that it's easiest to go through and learn all the rules, but by the time you learn all the rules you'll find out there are no rules. But, it is very tough to just come up with something original that isn't crap without any prior knowledge of music, but you know, it had to start somewhere. Basically what I'm trying to say is, no one can tell you what it is you are trying to accomplish, they can only guide you and give you advice. But anyways, I'll clue you into some of my musical processes.

First things first, learn your instruments. Familiurize yourselves with how they work, what they do and so forth. It helps especially to learn what is in a standard drumset.

The next step is to listen. Find out what music you like, listen to it. Try to get a feel and understanding for the notes and scales that they use. Then it's always good to listen to who inspired them. Eventually you'd be able to trace it back to jazz, to classical, to some dude with a rock in a cave. Keep in mind the instruments you learned in the first step. What instruments are playing? Guitar, Bass, Synth, Violin, Clarinet whatever. Keep in mind the beats of the drums, which parts are they hitting at what moment, the bass drum, toms, cymbals, hi-hat?

The final step is to learn your bonehead musical notation. I don't know how to read sheet music, I don't need to, I'm a guitarist (joke), but it is always a good thing to learn standard musical notation.
--------F---
E
------D-----
C
----B-------
A
--G---------
F
E-----------
That's basically how the notes are set up for a treble clef, which is usually used for higher pitches. The base clef is used for lower pitched instruments.
You should be able to notice the bonehead acronym they teach you in kindergarten for the notes on the line and the notes between the lines. The notes on the line are EGBDF, or Every Good Boy Deserves Fudge, or Eastern Goblin Breaks Deli Factory, or Eat Great By Da Fridge. Come up with something, memorize it. Then the notes between the line spell FACE. 'Nuff said.

From there, try to learn some simple scales. Every note in existance falls into a catagory describing them as a letter. The letters range from Ab to G#. They go A A# B C C# D D# E F F# G G#. If you are using flats it goes Ab A Bb B C Db D Eb E F Gb G. Notice how there is no B#, no D#, no Cb and no Fb. That's because these notes do not exist. Don't ask me why, it's the same concept of a leap year, humans aren't perfect so we have to invent systems to correct our flawed systems. Keep in mind that flats and sharps are the same. A# is equal to Bb, C# is equal to Db, and so on. The easiest way to illustrate sharps and normal notes is to look at a keyboard or piano. All of the white keys are normal notes, while all the black keys are sharps. So if you start at C on a piano and go up only hitting white notes, you'll be hitting CDEFGABC and so on.

Now getting into scales. If you memorize the notes from A to G# (or Ab to G), you already know a scale. That is called the chromatic scale. The chromatic scale is broken up into a 1/2 between each note. Keep that in mind as well, between every note is a 1/2, and if you skipped one note that would be a whole step. The next two scales that are easy to get a grip on are the Major and Minor scales. Every scale is named by the first note in the scale. For instance, if you played a Major scale that orignates from C, then it would be a C Maj scale. Speaking of C major, that is the base for the major scale, and the easiest to remember. The C Major Scale goes like this.

CDEFGABC

Sounds simple, right? But to figure the how the scale works, you just have to count the steps between the notes.
C---D---E---F---G---A---B---C
--1---1--1/2--1---1---1--1/2-

So knowing the formula for the C Maj scale is 1,1,1/2,1,1,1,1/2, you can figure out any other Major Scale.

E---F#--G#--A---B---C#--D#--E
--1---1--1/2--1---1---1--1/2-

The most important thing to remember when you figure out scales is that you will always start and end with the same note. If you start with F#, you must end up getting to F#. If you pass it, you know you messed up. Try again.

Minor is a good scale to learn, because it is a huge contrast from Major, and it has a cheat scale to figure it out, like the C Major Scale.

ABCDEFGA Can you guess what minor scale this is? (I'll give you a hint, it starts with an A)
/retard

Now, it plays the same notes as the C Major scale, but the order that they are played grossly effects the tone of the song. Major has a much happier and up beat tone, while Minor is going to make the song sound a bit more gloomy and down trodden.

There are hundreds of different types of scales, blues scales, foreign scales, tones of stuff, expirement and do some reasearch to get that sound you're looking for.

Chords are another important thing to learn when writing songs, and can be figured using the scales that you learned earlier. A chord is more than one note played together simultaniously. Basically, if you take more than one note in one of those scales that you've learned, and play them at the same time, you just played a chord. For instance, from the C Maj scale if you play C, E, and G, you've just played a C Maj chord.

The last thing I'm going to go over is timing.

Whole Notes
Half Notes
Quarter Notes
Eighth Notes
Sixteenth Notes
Thirty-Second Notes
Sixty-Fourth Notes

Notice how each time you move down, the note is devided in half. The standard timing is 4/4. This is what gives each of these notes value, and how many beats are in a measure. I won't delve into it too much, but if you have the chance play with it in an editor that will tell you if what you did is do-able or not. But in 4/4 Time, a whole not will take up 4 out of 4 beats int he measure, the half will take up 2 of the 4, the quarter 1 of the four, the either .5 of the four and so on. There are ways to make these notes longer and shorter however, and they are the dotted note and triplets. A dotted note adds one half of the notes value to it. So a quarter note in 4/4 would go from 1 beat out of 4 to 1.5 beats out of 4. The triplet devides the notes value by 1.5 and are usually played in a succesion of 3 notes. There other similar modifications like the triplet, the fifth, the sixth, seventh, ninth, twelvth, and so on, that devide the note by a certain number and are played in a succession of the name of the modification.

Using these methods of songwriting, get yourself a midi program and practice. Start by getting a main kind of theme that you can add little parts on and well, just get creative. Like I said in the beginning, I can't tell you how to write a song, I can only give you the tools to write it and tell you how bad is sucks. But, then again, if it's what YOU wanted to do, then it won't matter what anyone else tells you.

Hopefully this article gave some of you some insight into the wonderous world of music, and I hope it wasn't too all over the place. Have fun.