I found what I think is skin cancer on my leg, can I go to the emergency department or I have to find someplace else?

Primary care. The best place to start is with you primary care physician or dermatologist.
Not usually emergenc. Skin cancer is almost never an emergency; in fact it has likely been there growing for at least 6 months. Typically you will have a better experience if you make a routine appointment with a surgeon or a dermatologist to see about arranging a biopsy, which will tell if it is cancer or not.