You may need to set up the Edimax for the specific Orange broadband parameters - look at the Orange set up details and compare them to your default settings on the router.
After that just connect a LAN cable from the router to both PC's and they should automatically find the IP address themselves (if DHCP is selected to automatic on the router).
You might find just plugging in and trying the internet will give you a connection but I assume you will need to enter your Orange UserName and Password on the router so it can connect automatically when it's turned on.
You will probably be able to enter your routers set up by typing in an IP address in your Browsers address bar. Typically it will be something like 192.168.0.1 but the manual will tell you what it is and also the Router Username and Password (which is NOT the same as the UserName and Password you need to access your Orange account!).
It can look complex but in reality it's simple once you've done it the first time!