How to set up LAN on the wall of the apartment to internet.

I want to use LAN on the wall to the PC, but it does not have internet, while I am using the router from XFINITY. My current situation is that I have connect  coaxial connection between wall (picture 1 ) and Xfinity router (a white tall one no showing in the picture).  so should I connect an ethernet cable from router back to wall (picture 1), or I should do something else on other side, like showing in other three picture.