Setup Wifi for Tablet and cell phone

I had to reset my modem as my connection was super slow and then I had to reset it again as it wasn't working, and turns out my provider has had some issues, but it's up and running now.

My problem is they would charge me $75 bucks to come in and have someone setup my tablet and cell so I can connect via wifi and since niether is finding this modem, they can fix it for me. I don't have the funds for them to come out here as I am currently out of work.

Can someone please tell me how to do this? On my tablet I have the wifi on and it's not finding this modem and also is there a way to rename the modem? When I got the internet service, they did that for me and now it's all gone. No idea where to go and how to change or how to access my password for the wifi? 

Thank You