i recommend walking and jogging-- soo good for you, and it feels great to build up endurance and speed (but start slow, so you won't be discouraged). also, do some strength training with dumbells or soup cans... bicep curls and tricep curls are great! jumping jacks are wonderful cardio and can be done indoors--- also, get a jump rope!!
also, a lot of colleges have on-campus gyms which are relatively inexpensive. certainly there's a weight room w/ treadmills and machines somewhere.
you can also do squats, crunches, pushups and leglifts ANYWHERE.
finally, keeping a nutrition journal is incredibly important--- you can get the calories/fat/carbs/protein values on the internet, and make sure you comment on your reasons for eating various things. based on that, you can make some informed decisions.