Next place your antistatic strap on your wrist, remove your motherboard from the antistatic bag, place the motherboard ontop of the bag and remove the CPU from its packaging. Ensure you have your motherboard manual to hand and locate the CPU slot. Your CPU can only fit into its slot one way, so do not force it into position, once in place there should be a clip you can secure the CPU in position with. The CPU should come with a heatsink fan. Refere to your manual for instructions on fitting your heatsink. There should be a series of clips and springs that hold the heatsink in position, there will also be a power cable that will plug into your motherboard close to the CPU slot.
Once the CPU is installed inside your motherboard you can go ahead and insert the motherboard into your case, there will be a metal plate on the back of your case that will require you to remove before inserting the board. the plate should push out with gentle force. you may also have to fit a the template for your motherboard onto the back of your case where you removed the origional plate, this will be supplied with you board, secure the plate with the fixing screws. Now refering to your motherboard manual locate the holes to secure your board. Your motherboard must not directly touch the inside of your case, you will notice that there will be spacers included with your board. now insert and secure your motherboard.