Hey buddy, congratulations on your new path. My advice would be to:
1) Learn how to lift weights. Master the big lifts such as squats, bench press, deadlift, barbell rows, overhead presses, dips, and pull-ups.
2) I would research and read Starting Strength by Mark Rippetoe and perhaps later on 5/3/1 by Jim Wendler. Both are great, basic, barebones training books that will offer a lifetime of great knowledge.
3)Eat a sensible diet. I don't even think you need to do anything drastic, just use your head and clean up your diet. No sugar, sodas, processed foods, etcetera. Just work on eating 3-4 balanced meals throughout the day made from whole foods. Make sure you eat, don;t starve yourself-- or cut calories-- just clean up your diet and eat a well balanced diet. Meat, veggies, good carbs sources-- done.
4) Get moving. Every day do something active for about an hour or two. Doesn't matter what it is, just set aside 1-2 hours to be active doing something you enjoy. It could be working on a project building some cabinets for yourself, going on walks, playing basketball, walk through a park looking for cool birds and animals-- doesn't matter just be moving doing something that you enjoy. I personally walk every single day for about 2 miles. That is my thing, I go on a good paced walk outside.
5) Get good sleep and try to keep the stress out of your life.
***Btw, if you learn that you hate lifting weights-- you don't have to lift weights. But, you should aim for an active lifestyle doing things you enjoy. I love to lift weights, that is why I do it. The day I hate doing it is the day I stop going to a gym and I find something else I like.
You're done man, do that and enjoy the process. Remember, small changes over the course of a long time lead to big changes in the future. Don't try to do everything at once, take it slow and you should really embrace and enjoy everything-- don't make it a chore or you will fail. Best of luck.