There are some great resources out there as far as learning what your tenant rights are.
I would highly suggest you visit the
www.HUD.gov website and search for the tenant laws for your state.
You might also want to check out EZ
Landlord Forms - they have articles and a forum specifically set up for people that don't know what to do.
However, if I may... you will not be able to bill your landlord (grandma) for work done and/or withhold your rent for that amount... unfortunately, it doesn't work that way.
Please let me know if there is anything specific I can help you out with.