My inner thighs are fat is that what causes my inner thighs to be dark and can working out and getting them slimmer get rid of dark inner thighs??????

Probably: The skin of your inner thighs is likely being chronically irritated from rubbing together or against your pants. This causes post-inflammatory hyperpigmentation, a darkening of the skin. Preventing this rubbing by losing weight and wearing loose pants will likely allow this discoloration to resolve over time, and will yield many other health benefits. Good luck!