Go to My account at the top of the catalog screen. Type in your card number (do not include any spaces) and your PIN.
Everyone begins with the same default PIN, "changeme", and the user ID is your library card number including the "D" and any zeros, but no spaces. To change your PIN, log on to the catalog with the default PIN and go to "My Account" at the top of the page. There you'll see an option to change your PIN (make sure you write it down if you change it!).
Note that if you log in before you begin searching the catalog, you will not have to re-enter your User ID and password each time you want to place a hold; the system will supply them for you and direct your hold to your home branch. Let us know if you have any other questions. See Catalog