Hello

Welcome to MFP!

There's a wealth of information here. A good starting place is the "Most Helpful Posts" sections under the Getting Started and General Health, Fitness & Diet topics in the community. Here are direct links:

https://community.myfitnesspal.com/en/discussion/10300331/most-helpful-posts-getting-started-must-reads#latest
https://community.myfitnesspal.com/en/discussion/10300319/most-helpful-posts-general-health-fitness-and-diet-must-reads#latest

These posts (also called "the stickies" because they stick around) were all written as normal posts by regular MFP members, and nominated to be "stickies" by other regular MFP members. There's gold in those posts! I learned so, so much from them when starting out. You could do worse to chip away at reading them, starting with ones whose titles pique your interest.

As an on-ramp, I think this one is particularly good:

http://community.myfitnesspal.com/en/discussion/1080242/a-guide-to-get-you-started-on-your-path-to-sexypants/p1

(Don't let the joke-y clickbait title put you off: It's full of serious, solid information.)

Wishing you much success with MFP!