The skin of my vulvar is slightly red. Do I have vulvar cancer?

Probably not. This is not a common appearance of vulvar cancer; they are more frequently masses, ulcers, or raised plaques. However, redness around the vulva can be indicative that something else may be going on, so it is important to have it looked at by a gynecologist.
See your doc. You should see your friendly ob/gyn and alert them to any changes in your exam.
Vulvar cancer. It is unlikely but possible. Vulvar cancer usually shows up as a lump, bump or mass. See your doctor if you have questions.