See your physician. If you think you might be depressed, please see your physician for an evaluation. S/he can also connect you with a psychiatrist and/or psychotherapist, as medications and therapy together provide the best results. Good luck to you.
Get evaluated. Realizing you have depression is half the battle. Get evaluated, your pcp would be the best person to start. He may treat you or refer you to a psychiatrist. Treatment depends on kind of depression one has. There are effective treatments both in terms of medications and psychotherapy (talk therapy).