It's more fun for us random people if you try a go at it - and let us critique your efforts. try going to pcpartpicker.com as a first start.
I will give you my 2 cents first - choose an i5 processor as the top version of CPU for gaming - though AMD isn't bad - I have the 8350. I7 is a bit more than you will need.
Also make sure your Power supply is made by either Seasonic, FSP, Zippy or Superflower - all are top tier manufacturers - but are not neccesarily the brands. For example - XFX PSUs are made by Seasonic.