Do at least one active thing per day. Doesn't matter if it's just setting a goal to walk. Do something, anything. Move and eat smaller portions. Cutting out processed foods helps too. Good luck and don't watch the scale. Gauge your progress on how you feel.
try and walk twice a day, maybe early in the morning, and then go on a night walk after dinner.
after that, try to work yourself up to jogging or running, or biking.
swimming is also great, that way it doesnt hurt knees or joints....
all while doing this try and keep eating healthy! You'll get there!