You haven't defined your question well enough for us to be much help. It is too open ended. Sounds like you need to find a user manual or owners guide and start reading. Then you can ask more explicit questions.
That's a substantial tape library. So, you must be backing up a bunch of stuff. What platform/distribution are you on? What are you backing up? What software are you using? Has your setup got any history? Is it now not working, and the person who set it up is gone? Or did you just acquire this thing? What have you tried so far? What happened?
The more detail you can provide, and the more explicit and pointed your questions, the more likely someone will be able to help you.