I need help losing weight and stayin in shape!?

I'm 21 and trying to have a health diet and get in shape but I cant help to eat candy, chocolate and munches all day. I start exercising I go jogging for 20-30 minutes and come home and do about 100 sit ups and 30 push ups. What should i do to help see some results. Should I work out more and when should I work out morning or evening>? also, when should I eat> before working out or after and how long should I wait?