How do I connect my wireless router to my modem and still have a wired connection to my PC?

My sister and mom both have laptops. I have a desktop pc. I have the wireless router connected to the modem, and the router connected to my PC. My sisters laptop has an internet connection, however my wired connection to my pc is not working and my Xbox is also unable to connect to the wireless network. I followed the instructions given but still no connection. What am I doing wrong?|||You might be having trouble with the connection type. Check it is set for your type of service.