In the rear there is a cross member above the rearend; there are 2 shock mounting positions (one on each side), a bolt goes through the cross member, through the shock and then the other side of the cross member with a nut on one side (typically on the front end side). Depending on the year of your car, there should be an access hole in the trunk (either facing rearward or facing straight up) unless the floor was replaced and the holes have not been cut. That said, you can usually get the bolts into the cross member without the holes, however getting a wrench on the bolt or nut can be a challenge without the holes but it can be done. The bottom of the shocks slide onto the stud on the rear end plate and are held on by large washer and nut with a lock washer.
On the front, the shock stud simply goes up into the shock tower; there should be a washer with a bushing on the bottom side and a bushing with a washer on the top side. Bilstien provides a nut to tight the shock and a lock nut to keep the first one from coming off.