Go to WorldCat Discovery, then click the "Sign In" button at the top right of the screen.
Choose your school, then sign in with the same username and password you use to login to Blackboard.
Now in the corner where it used to say "Login," you should see your name. There is a dropdown menu to choose options beneath that, so choose your name and then choose the "My Account" option.
Once your account page loads, you will see a list of the materials you have checked out, and "Renew" buttons if renewal is an option. The display will also show the dates that your items are due.