You can choose to allow patrons to borrow and/or return items from any PC/MAC, or mobile device, when logged in. This is handled in the settings for rights.
For the librarian loans and returns are handled from the Desk menu.
Desk > Loan
Desk > Return
For loans you type the user code of the patron, and then the barcode or ID of the item(s).
For returns you type or scan the barcode or ID of the item(s).
The item(s) are checked out according to the rules in the settings for loans, ie. based on the type of item or the user group of the patron.
You can manually change the expiration date of the loan by clicking in the date field.
You can send an email receipt to the patron at the end of the transaction.