You can place holds for most of the materials found in the library catalog by logging into your account, searching for the item, and then clicking "Place Hold". You will then be able select the library at which you would like to pick up your hold. You will be notified by email when your hold arrives.
You can check the status of your holds by logging into your account and clicking on the Holds tab. Holds that have arrived in the library are marked with a green exclamation mark and "Pick up by DD/MM/YY" (after which date they are returned to their library of origin), items on their way to you will be marked as "in transit", and those that are checked out to another patron or not yet available will be marked as "pending".