Google is your friend.
There are many websites which offer tips & tricks on building your own PC.
Building Your Own PC, Part 1: Know-How for Do-It-Yourselfers : Building A PC System - Tom's Hardware
Building Your Own PC, Part 2: Assembly Step by Step : Guidelines For Building Your Own PC - Tom's Hardware
Honestly, it's really not that hard. It's the same as buying a table and reading the manual to assemble it.