Welcome! Here are some exercise ideas:
Taking a walk is really cheap and good for you. If it's cold where you live, go to a covered mall (but skip the food court!
).
There are a ton of exercise videos/DVDs available, and sometimes you can get them used (e.g. through Amazon).
A membership at the YMCA doesn't cost very much per month, and you have access to everything there.
A set of low-poundage hand weights can do a lot for helping to build healthy muscle, and they can be had cheaply if you shop a bit.
Sometimes there are classes at the Y that anyone can sign up for, even if they aren't members. They have low-impact versions and senior versions where I live.
Jay