Click the 
button in a catalog search to access your library account information. You
will need to type in your UW Colleges ID number and type in your last name
(in lowercase) to login.
The items you have checked out will be shown under the heading "Items Currently Checked Out to You". You can check the box next to the item you'd like to renew and then click the Renew Items button. The status should change and give you your new due date.
Please ask if you have problems.