Take the bolts out and have a fluid pan ready to catch the fluid. There will a filter that you can either pull out or unbolt. If it is the pull out style then after you pull it out there might be a collar still left in the hole that you have take out. Push the new filter on(if it is that style) or bolt it back up. Cleanthe mating surfaces of the pan and transmission. Put the gasket on the pan and torque to spec.