Stereo

I have a 1992 pontiac sunbird se 4 door and it has the little box stereo init, and i want ti put a aftermarket stereo in it, how do i do this? How ideas on how to cut the dash and do this???? Also i need to replace the winshield washer pump. How do i get to this ? from behind the tire well???? PLease repply!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!