I may have asked a question in the intro forum--apologies if so

I have used a Nuc with Debian for some time while living with my husband. He was my technical advisor and expert, and he made all the decisions. Suddenly I'm on my own and I want to try to manage this as well as I can. Can I use wifi and how do I do it? My new apartment has a Linksys router provided and I assume wifi is provided. I am typing on a laptop with an ethernet cable to ask these questions.
The router has a phone number that doesn't work for technical support.
User name an password are provided for the router.
I don't know where to enter those items to get online.
Obviously I need help.