Building computers isn't hard, just take your time in seeing how the parts fit together and put it together. Take a little extra care with the heatsink for the CPU - you only want to attach it once so the thermal paste between the heatsink and CPU is at its best. If it uses push pins (I've never used an AMD stock heatsink before), then push them in a X pattern (top left first, then bottom right, then top right, etc) for even pressure. Everything else is pretty straight forward. Hardest part is tidying up all the cables at the end.
Also, clean your hands before starting, and make sure to touch something metallic to ground any static energy from your hands. There are many stories about static shocks killing computer parts, although I've not had it happen to me yet (maybe because I always start by grounding myself).
For specific advice, feel free to ask specific questions.