It should be fairly easy mate, just take your time. Everything will only fit into one slot, if you feel like you're having to force anything too hard then you probably are and it's not meant to be there.
Take a good picture of the components in your current case, so that you can see everything - You'll be able to refer to this later if you get stuck. Dissasemble and remove the components from the current case and start carefully installing them into the new case.
I find it's easier to start by throwing in the optical and hard drives, followed by the PSU (Power Supply Unit) and then the motherboard. All the power connections will only fit where they are meant to, sometimes they can need a tiny amount of force to go, but not alot. You should be able to look and see if the connection will or will not fit.
You can leave the RAM, CPU and CPU cooler all installed on the motherboard when removing and installing it to save hassle and time, the only thing you'll need to connect back to the mobo is your GPU (again, will only fit in the right slot), SATA/IDE cables (these should be very easy) and power connections.
You can only learn by doing and if you take care there's not alot that can go wrong really. Good luck, have fun
EDIT: Takes me a couple of hours with advanced cable management, if I wasn't so fussy about that then I could knock them off in an hour easily.