Dieting advice!! Please help

with my first baby I gained ALOT of weight. I was just lazy and everyone waited on me had and foot. I lost most of it at work. (I walked back and forth through a factory for my job. 8-10hrs a shift constantly) well after my second my husband and I decided I'd become a stay home mom. Well I gained weight. After 2 yrs I'm fed up. Going to start the gym Monday. But I need diet advice. I've never dieted before. Don't want to spend the money on weight watcher etc. So give me some good diets