I'm man and I m18 but my butt is very small help me to work on big butt

I know a few butt toning exercises...

If you can get some ankle weights it would be good, they are just little weights (not too heavy) that you can strap around your ankle.
Stand in front of a chair and place your hands against the back of it.
Lean slightly against the chair and move one leg backward in the air as high as you can. Hold for a second or two and then put back down.
Repeat this until you can start to feel a burn in the back or your legs and butt.

I did a little diagram for you... it works for me :)

Squats and deadlifts. Also step-ups onto a high step or stool. Stiffleg deadlifts.