Heather,,,, are you saying that you don't have an Owners Manual or Service Manual or you don't have a Manual Transmission.
A Manual transmission is fairly straight forward, but an Automatic Transmission is a whole different bucket of worms, because you can't just drain (all) of the fluid. Recommended service is a full "Flush & Refill". Almost every modern car service center has the machine to perform that service. And it's warranted.