I need to add a cooling fan and Heatsink for my Gateway laptop model 7322 GZ. Do u have any instructions to share with me? My laptop is cutting off the power after a few minutes and I guess it must be over heating.

I guess your problem could be related to overheating. Can you hear the cooling fan spinning? Does your laptop feel hot on the bottom?
Before you take it apart, try cleaning the cooling fan and heatsink with compressed air. Find an air compressor or buy a can of compressed air and spray it inside the air intake. This will remove 80-90% of dust.

Take a look at other laptop in Gateway category. It’s possible that one of them is similar to your laptop.