You can renew your books online if it is before the due date, your account is in good standing, and no other patron has placed a hold on the items. You can also renew in person at the Circulation Desk, call (210) 486-4500, or use the chat box on the library homepage.
To renew online, sign into your library account, view checkouts, and choose the Renew button under "Status." Your new due date should show immediately if the renewal was accepted.