Renewal:

A user can renew a book after issuing. Users can be renew through online by login to your account, select the renewable item(s) and click on renew or user can came to the library physically with the books and ID card and renew the book(s). 

However if any user reserve any issued item(s) then the holder of that particular item(s) can't issue or renew the item after reserve.

Reserve:

If any book(s) is issued to any user and no copy is available in the library then the user can hold/reserve the book(s). The user can reserve the item(s) online by login to their account after searching the book in OPAC or asked at the circulation counter. A user can reserve maximum two books. One book can be reserved by many users. The user can have the book(s) withing 2 days after returning by the previous  user. The user will be informed through e-mail about the availability of the book(s) in the library.

The process of renew or reserve a book(s) is given in the link below

If you face any problem while renew or reserve, you can contact to library staffs.