Remove the battery.
remove the screws from the smaller back panel, the one you can see your memory thru.
Lift off the plastic cover and you can see the memory. You have the laptop upside down, battery compartment away from you and the front of the laptop near you. The wireless card is just to the right. It has two gold connectors attached to it. Carefully using a small screw driver or plastic knife pry up on the gold ends, they are pressed into small receptacles like on a 9 volt battery. The card will have two small screws holding it in place and plugged into a edge socket. Install the new card in reverse of taking the old one out.
Take your time end be careful not to poke into the motherboard with your screw driver. I have hard thumb nails and am lucky as I use my nail to flip off the connectors.
Good luck