I get really bad black heads and pimples on my inner thighs i don't know how to get them to stop. also pimples on and under my breast but i don't why?

Bad black heads: on the thighs - it might be from rubbing on clothing causing irritation of the skin leading to pimples and blocked sebum glands. The same for the area under your breasts. I would use a mild facial scrub which will help remove the black heads and bring the pimples to a head. You can use any of the OTC acne medications as well. Under your breasts I would make sure the area stays dry.