How do I make my dog a Emotional Support Animal?

My dog is a great companion for me but my neighborhood is trying to kick him out due to deed restrictions. My dog helps me to stay calm and my behavior has changed since I've had him because I feel like I need to be strong and stable for him. I have pre-existing mental condition for which I have been attending therapy and taking medication for over the last 10 years. I fear that if I am required to give up my dog, I will not be able to handle it emotionally. My co-worker told me about Emotional Support Animals and I feel my dog and I qualify but I'm not sure how to go about making it official. My doctor has already written a letter of recommendation but I don't know where to send it. Any guidance would be helpful. Thanks!