Welcome Back. I don't know how you can change your user name. However, I did a search on "California" in Spark Teams search under the Community tab and found the Spark California team with 422839 team members. You could start there.
Give yourself a big hug for making this positive choice for yourself. Take your time to explore all the resources available for you here. It can seem overwhelming because there are so many resources to choose from. Two to consider using are the Nutrition and Fitness Trackers. As to other Spark Teams: do searches on your goals, interests, hobbies, whatever. Then join one, two or more Spark teams. You'll enjoy getting to know these folks and giving and getting lots of encouragement along the way. It's all good. Enjoy the journey!