Router setup trouble (help!)

I want to install the router I am renting from XFinity so that I can use the internet plan that I bought from XFinity, but I don't know what I need to do to install it. It's been a few days of trying things so I thought to ask for help if I can find it.

I have an XFinity router which has a bunch of ports on the back. It came with two cords: a double-male ethernet cable and a  double-female coax cable. The place where I want to hook up my router does not have any coax cable outlets, but it does have a dsl outlet. The router also has a dsl port so I hooked up the ethernet cable to my computer and then the dsl cable to the wall. This did not yield any results, though the simple act of hooking up the ethernet cable brought up a new window prompting me for my login information (which is apparently always incorrect?).

According to a step-by-step guide the endgoal is to have the US/DS and Online lights on, with the 2.4Ghz and 5Ghz lights blinking. To do this I must hook the ethernet cable to my computer and then the coax cable to a wall. There is no mention of a dsl cable, yet the ports exist.

I ordered a coax-to-dsl adapter off of amazon, but the ports for ethernet/dsl look very similar so the adapter I ended up getting was coax-to-ethernet. I hooked that up to the computer (which has one sole ethernet port) along with the dsl cable to the wall to no avail. If it wasn't already clear, I hardly know what I'm doing.

I have wasted enough time and resources. If anyone knows how I can set up my router in a room with dsl ports and normal outlets using a computer with one (1) ethernet port, please let me know. Alternatively, if this is not the correct place to be asking for help, a redirection would be fantastic.

Please and thank you!