Kay, So I went to this bookstore we have in Texas and they had a bunch of DnD books, so I bought Players Handbook (3e) Players Handbook II (3e) DM guide (3e) and Monster Manual (4e) I'm not a seasoned DM, Like I've literally only Played once, back when I was 14, and I hardly remember anything. ~So any advice, or should I just stay within the 3e books?
Rules for different versions are mostly incompatible.
There are some conversion guides available on the internet if you if you want to mix content from different versions.
As AceCalhoon points out in the comments, you can also use the d20srd site to find monster stats for 3e games.
I think your Monster Manual will get some dust.
4e and... anything else are really incompatible. While 4e is a good system (if you like the style), you can't do much with it if you don't have the other core books available to understand the rules.
Players Handbook I & II and Dungeon Master's Guide are already excellent resources to start playing 3.x, so I would suggest sticking to them for now. If you want to really improve your resources, look for the Monster Manual for 3.x!