If you have ever put together Lego, you can put together a PC. It it mostly just looking at plugs and ports and figuring which way it goes in.
all the ports and plugs for pretty much every cable are designed to be only inserted one way, if you tried otherwise you would have to break the plastic.
Heres a pretty comprehensive video guide from NCIX.
http://www.youtube.com/watch?v=HIJx6Y3tofg&feature=plcp
Two things I would differ from the guide is putting on the CPU cooler before mounting the motherboard, regardless of cutouts in the case, its just simpler.
And always testbench the system before putting it in the case. So assemble the CPU (and its cooler), Graphics card, RAM, HDD's on the motherboard and hook it all up the power supply and see if it works before you go to the effort of putting it in the case. Make sure its on a wooden table or the box the mobo came in so you don't short out anything.
And another on Cable Management (which you should do)
http://www.youtube.com/watch?v=ERhxmzQR6xA&feature=plcp