Fez...
double check the water lines leading INTO the toilet to make sure there are no pin hole leaks there...
if you can't find the source of the leak...dry up as much as possible and see if it gets worse...if it does get worse, you need someone to help you-it could be very complicated and dangerous.....put a dry towel behind the toilet and check on it after 10-15 mins....if you cant find the source, don't let the water to continue to leak....down in your basement there will be a water shut off (trace it back from your water meter)...turn off the water pressure if you must so someone can look at it for you. Water can be VERY damaging if let running overnight...you may have to tear down a sheet of drywall if there is a leak in a water supply line in the wall...
owning a home does suck sometimes.....I would suggest buying yourself a home improvement/fix it book, they are very helpful....go to home depot/lowes, they have a nice book that shows almost anything you might need to know....
http://www.homedepot.com/prel80/HDUS/EN_US...ID=9876&pos=n16
don't be afraid of getting your hands dirty....its how you learn...maybe you don't fix everything but you'll get a better picture on things....
Good luck...alot of home improvement/fix it projects are not complicated when you look at them closely.....it can be fun,frustrating and very satisfying when you actually fix something on your own.....
I wish you luck and remember....do not let the leak to continue overnight....you can do it....YOU CAN DO IT!!!