not bad...
definitely go for anything other than the computer mic...lol I think a preamp might get you recording into the soundcard.
someone mentioned strum pattern...its like too much "down...down...down...down" 1,2,3,4
you know, create a rhythm, like up...downdown...up...down" to make it more interesting. 1,2,3,4 is for the bass drum.
multitracking: you record you playing the guitar of the song after you have it really down. Then, you go back and listen to the guitar track softly while you record the singing part. That way you can really get into the guitar track without worrying about hte singing. Then, you can burn a cd off, and sing to your song for a couple of weeks till you think you got it down, then you lay down a vocal track. When you record tracks separately, you get a chance to EQ them and add effects and stuff. EQ is like when you adjust your home stereo eq so you like the "sound", except you can do it separately for each track.
dont make ten other songs...keep arranging and working on THIS song. you got a start with it. dont get discouraged.
someone already covered dynamics. good first effort.