I've been playing for about a year and a half now and I really want to write my own melodies. I've just been playing the minor(?) pentatonic and the natural scales up and down(whatever they mean). Some songs here and there but how do I go about improvising? How do I make chords? I've also tried to pick up some books about guitar theory but right after they mention things about keys or what not i get confused. I haven't found one book that's comprehensive on guitar theory. Help?

first of all there is quite a bit of good information over on this site. i would recomend by reading on the idea of what scales are, and intervals, from there you can begin to easily construct your own chords.

with that being said, my approach is the following, listen to yourself playing, prefeably record yourself. and try to sing along or hum what you are playing melody wise. and then try to fix it till you get something you like.

good luck.

check the theory thread in this forum, it's a pretty good intro, even if i say so myself, and many people have linked to ibreathemusic.com for help too.

feel free to shout with any and all questions! :)

I wouldn't focus specifically on guitar theory. I learned everything I know just by studying music theory. Instead of focusing on how it all works together on guitar, focus on how music works, then focus on how to apply it all to guitar. At least, that's my 2c.