My ceiling fan isn't controlled by the switch on the wall. All you do is use the pull cord to use the fan. I'm trying to install a light and need help with the wiring. Any suggestions?

If in conduit, and you can fish wires to a box, that can be done.
If you are not able to run wires from fan to a wall switch, or a new wall switch location. You can add a receiver in the ceiling Fan canopy, then you can control by a handheld battery powered remote, and usually includes a holding bracket for mounting on wall.
Plus, you can control brightness and Fan Speed.

Do you mind the light being controlled from the pullchains, or are you hoping for a wall switch? Or remote?

What make is the fan?