Where to start on losing weight?

I was always in shape until after I had my kid, and I was hoping I’d go back to my pre-pregnancy naturally after my kid, well 2 years later, nothing. Now I wanna start doing something about it, I currently weigh 145 lbs, pre-pregnancy weight was 115, so that’s my goal weight, to lose 30 lbs, but I don’t know where to start. I’d appreciate it if you could shoot me some advice, because I really want to start feeling good about myself again. Getting sick of the thoughts of putting myself down.