Hook-up wireless router with PC that receives its signal through the phone

I' moving and bringing a Dell laptop into a house that has a desktop computer that receives its signal through the phone.  The router I am taking is set up for wireless, and I want to hook up to a wireless signal.  I imagine once I get the signal, I will find a local wireless signal, but how do I set up the router?

Thank you, very much.  I hope you have a great holiday.