[Help - First Time] Building a Computer for MMO's

I'm going to be building a computer to be used for MMO Gaming. It would be my first time building a computer and i don't really know what i should be looking for. The games I'd be playing right now would be StarCraft 2, and a few f2p MMO's.
In the future I'd like to play games Like Blade & Soul, Guild Wars 2, and Diablo 3. I'd like to play the games on maybe not Ultra settings but on high if that means anything.

I won't be using the computer to be playing anything like MW3, BF3 or any computer games like that

I need to keep the price at max $500 but as always the cheaper i can go the better   .

Also any tips on a good monitor would be greatly appreciated but is separate from the max 500 i can go for the computer

I'd really appreciate help on what parts i should buy, and useful links for help with building it

I'm Terribly sorry if I'm asking a lot but I'm really new to this type of thing and i'd love all the help i could get

Thanks A TON!