Newbie over 50

Hi. I'm 55 and I weigh in at a slim 290 lbs. I actually joined last Sept. but never did anything here. I'm sick and tired of being this big and decided to do something about it .... finally! I joined a gym. My goal is just to move 3 x a week, at least and lose weight. I have 2 kids. I started young and they're still in school. My son graduates this year and I don't want to look like I do now for his big day. My goal is to lose 30 lbs. by his graduation.