How to setup Password MikroTik router V.5.6

Good day,

the wi fi on my router is open , I want to set up authentication for it ,
the router model is MikroTik RB2011UiS-2hnd-IN model

I tried to use 192.168.88.1 which is the default IP , It does not work.

the router is plug on the Vodacom broadband network which has its own range. I tried to reset it , it does not work

please advice for the solution.