Put the number pad into the new cover and push it down
For the power button, I recommend using blunt nose tweezers to put the button in with the slope on the top of the button going down towards the speaker hole, then using a spudger to push it in
Using pointed tweezers can put holes in the power button and possibly break the button, only use blunt nose tweezers
Make sure the two tabs at the bottom of the cover go into the phone first at an angle, the push the top of the cover in until it clicks and then you are done!