I'm kinda in the same boat you are, but i found a magazine that leads me through step by step and a site. So now i'm just waiting for the money to buy everything.
If you can find a tutorial it'll help immensely in exposing some of the inner workings of building it. There is a tutorial in pcmagazine from awhile ago which is what i'm working from otherwise you'll probably be able to find one online.
The site I'm using is pcpartpicker.com which allows you to build your pc online from an array of parts lists which can be daunting. This site, however, is not a build it for you and there's no commitment. It's more of a tool to check for compatibility issues, give an estimated price, and much more. Also you can set up a forum for people to critique your build, offer advice and the like. If you have time to wait, you can also set it to message you when prices drop to a certain amount.
Here's my first build, I just went through the parts, and picked and chose based on what i thought i needed, price, and reviews i found. Also at the bottom you'll see a bit of advice given to me by a fellow user.
http://pcpartpicker.com/user/Tyverus/saved/2xbypg
This second build is after i made a forum for the first one and got advice from some others. This is probly the build i will use when i get the money since it's roughly the same price and gives me plenty of headroom for streaming and gaming.
http://pcpartpicker.com/user/Tyverus/saved/gC4Pxr
Finally here is the forum i made to get advice.
http://pcpartpicker.com/forums/topic/54919-build-research-looking-for-opinionsthoughs
Hope this helps!