My original router, connected to my ISP's modem is an Archer C7 on the main floor. Its wifi signal can only go so far downstairs due to a concrete floor so I picked up an Archer C50 to place downstairs. I can connect the C50 back to the C7 via an Ethernet. 

Question, where do I go from here to configure the C50 downstairs to be a part of my network and be able to not only connect the Xbox, the smart TV and a laptop or two via Ethernet but also have a better wifi signal for the wireless devices being used downstairs.

thks.