Your router is a hardware device that will sit between your internet modem and your pc.
Sometimes, it is a combined device that has both modem and router functions.
The model number of the device should be on a label somewhere.
If you are using ATT or Comcast, it is likely to be a combined device.
One can call Comcast/att support for help, and that is likely a good thing to do.
Download the instructions for your router.
google to find that.
What you can do and how will depend on the specific hardware.
There should be a web based app that the router uses that lets you log in to a whole bunch of complicated options.
Most you will not need.
Look for the way to change the default password that lets you access the router.