Is Every Tripod Universal? How Tripod Heads Install
It is not always possible to find a universal tripod which can fit any head attachment for your camera. Most tripod manufacturers also make a series of heads which can fit onto the top of the column, and you'll usually buy a series of heads at the same time as you purchase a tripod. If you have bought a new head, then you should check that the device will fit into your old tripod.
Installing a Tripod Head
A tripod head should be inserted into the top of the center column. If you are using a new tripod, then you may find that there is a small protection sheath over the top of the mounting screw. In order to fit the head, you should probably remove this sheath, and put the bottom of the head over the screw so that the threaded hole in the tripod head is lined up with that screw.
You should then tighten the head onto the screw. It is important not to cross the threads in the hole, as this will damage the screw and prevent it from turning. Tighten the screw down, and then tighten onto the column using a screwdriver.