How can i whiten my ocks?

I have a problem regarding my ocks..it's kinda dark and has a pimple-like underneath. that's why I couldn't wear my favorite two piece. please help me. it's kinda embarrasing! they told me that the pimple-like thing is due to some hair follicles that was caused by heat coz with the clothes i wear--what's the real cause why I have those? thanks, help!