Whiteheads or pimples can occur anywhere on the surface of the skin, including in the groin and vaginal area. Having pimples in the groin is no more serious than having them anywhere else, and you can treat them exactly the same as you would treat a pimple elsewhere on the body.
Making sure that this is just a pimple and not a sexually transmitted infection is important, however. One of the common sexually transmitted infections that causes sores in and around the vagina is herpes. Herpes sores are actually small fluid filled blisters, usually sitting on top of reddened skin. They may pop and form small ulcers which heal slowly, and they are usually painful. Syphilis also causes ulcers in the vaginal area; they are usually larger than herpes sores and they are typically not very painful.
Based on the description you have given, I doubt that what you have is a sexually transmitted infection. However, it is always worth getting testing, especially if you have been having unprotected sex. If you go to see your primary care doctor
, they will be able to perform some simple tests to make sure that you do not have a sexually transmitted infection.