How to lose 15lbs fast?

I need to lose 15lbs fast! before I go back to school… I want to know if walking and running will make me lose weight faster than pushups, squats, and situps??? im 16 140lbs 5’1 feet. want to be at healthy weight!
I can’t always reach gym but I try to jumprope 10min at my house. I sit most of my day. I wake up like around 10am don’t get hungry until after 12pm usually have some whole grain cereal with half a banana and a little organic soymilk I then eat around 5-7pm again when I get hungry and start with a big salad with lots of veggie and beans and some chicken maybe some fruit later. if im still kinda hungry or maybe just craving something I eat a PB&J with a glass of milk. then wait until im sleepy which is always after midnight maybe even 2:30 am.

I need to sleep more and be a little more active to get hungry, be hungry at the right times and have control basically and don’t know how. I want to have a routine and obviously burn more calories than I consume. I have a jumprope at home and two 4pound dumbells. I don’t know what to do at the gym but walk and jog an hour on a trimill (however you spell it) >.< everytime I go, about 3 times a week.

I need advice on what to do. Tips. anything to help me reach my goal fast. please