By talking to others who have experienced it to a doctor to help u prescribe medication talk to a counselor or keep doing the things that make you happy so your not sad and search for ways online to help you get rid of depression
Therapy really does help because they can help you understand how to change your thought process. In my experience medication doesn't help on it's own. It is treatable as long as you are willing to take some help :) good luck and if you can't afford therapy try talking about your emotions with someone that will listen to you and not judge you and stay around positive people.
Well whatever depression you have you should try talking about it to someone close to you like your Dad or your Mom. I know that I talk to my fellow officer's about depression on the job. I get depressed because I wonder to myself every morning I wonder what if I don't make it home and I possibly get.... shot possibly and what would my wife do but I try not to worry about that and go on but by talking to my fellow officer's it makes me feel better :)