First day counting calories, Feeling overwhelmed but excited.

Hello, Today is my first day on myfitnesspal and my very first time counting calories. I'm just going to jump right into my story.. I was always naturally thin, but experienced many years of homelessness and dropped to a dangerously low weight. Long story short, i now have a home and a family and life is good. Except for the fact that once i had the ability to eat food on a daily basis, and experience all these new things, i rapidly gained weight! I was never really educated about food or diet, and was shocked by gaining over 100 pounds. It's like i just woke up one day and realized how big i was (and still am). I have fallen into a habit of emotional eating, and also deal with chronic pain issues. I feel motivated to be up and about and wanting to do things, but once i try the pain is often crippling. I don't know if i can lose the weight through diet alone, i would like to be more active and have tried to create a reasonable fitness goal, but i think i over did it today and am now hurting as a result... I intend to stay motivated and stick with this, but this is just day one, and i think i will need help. I don't have any friends to help me on this journey so i thought if i made this post, and somehow get involved, i will be held accountable and less likely to give up. I am so glad this site is here! I really hope if i commit, my quality of life can improve. Thanks guys