It may help you to see one example to decide whether this possibility interests you.
To log in, you must give your identifier and password. The number of your patron card (which you can normally find below the bar code) can always be used as your identifier. It is also possible for you to set another identifier that is easier to remember with the help of the librarian in the library. In this way you can check your status even if the patron card is not on you.
For security reasons, no reader can use this function without a password. If you have not gone to the library and set your password (or have your password set) in TextLib, then you can log in by giving your birth date.
For example a reader who was born on 25 March 1970 must give the password "19700325".