This is such a learning process. Many of us started out feeling confused, and many people start with that sentiment. The good news is that there is no way to screw up. We build this up in our minds so much, but it's really a trial process. Try one thing, try another, see what works and what doesn't...
Step 1 may be to figure out a diet approach that works for you. Some folks count calories, some do weight watchers, certain kinds of eating plans, etc. Sometimes taking a browse through the different subforums can help give an idea of possible approaches.
Sometimes folks start by deciding on 1 thing they'd like to change, perhaps add to their diet or eliminate from their diet. Sometimes that 1 thing is water, sometimes it's not even about diet but about exercise, etc.
I know it can feel really overwhelming to jump feet first into something you don't feel all that familiar with. I feel that way with my work, so what I did was categorized it and created different goals. Ex in this case: diet goals, water goals, exercise goals, and so on. This way, I was taking a comprehensive approach and doing my best.
Whatever you decide, do know that you can do it! Good luck!!