Have you gone to confession? The priest who hears your confession should be able to guide you in this.
It’s usually best to return things to the people you stole them from. If that’s not possible, sometimes it’s recommended to make restitution in another way — for example, to make donations to charity roughly equivalent to the amount stolen. You may have to do this over a period of time.
Anyway, if I were you I would ask the priest about this next time you go to confession.
