For the physical side, firstly you'll need to detach your heatsink+fan from the board. After you've done that (There should be a guide for every type somewhere, try google) there'll be a little metal arm next to your CPU socket, which sort of "unlocks" the cpu from the socket. Make sure you bend this lever back as the CPU can become damaged if you remove it without doing so (Although it takes a lot of force without unlocking it).
Sometimes the cpu will have become stuck to the base of your heatsink, there's not a lot you can do here apart from either heat it up a little and twist, or just yank it off the board and risk taking the cpu with it. Hopefully if you have to do that it won't damage the cpu, but it's a chance you might have to take.
Then it's a matter of reversing the process, simply push the cpu into the socket, bend the arm down and attach the heatsink. If the heatsink doesn't have any thermal interface material (a sort of metallic grease used to improve heat transfer) then apply a little, there are loads of guides on how to do this dotted around the net.
Software wise I'm not entirely sure, but I know a lot of issues can be fixed with AMD's dual core optimiser so make sure you get that.
Sorry if that was all a bit basic, I just don't wanna miss anything out!