Hello Blankso:
Welcome aboard.
A couple of things: if you WANT TO write music, then I suggest you enroll in a music program at a post-secondary college or university. Also, drop the WANNA. No one will take you seriously otherwise.
If your primary interest is video games and popular music, then I think you might be in the wrong forum, though you can certainly pick up some of the basics (which are the same in all kinds of music) and ideas here.