If you have "some"... then you probably got them from the wild where they belong. If so, release them. All you will do is end up killing them.

If you bought them from a pet store, ask them. There are many species of lizards and they may have quite different food requirements.

Most lizards eat insects. Horned Lizards, for instance, specialize on ants.

Why keep pets if you don't know even know what they are or how to care for them?

First of all you till me that what kind of lizard is it?