If your wireless router has a manual with it, please follow the instructions in it.
These steps are basically the same in nature.
- Connect the wireless router to your main network / directly to your internet connection.
- The wireless router will usually have many ports. Insert the connecting end of the cable (which connects to your main network or the internet) into the lone port (it will usually be separated from the others and denoted by a different color).
- Turn on the router.
- Connect the router to one computer and configure it (you will use one of the 'other' ports).
- Optionally, you may either keep this connection or not, and add more computers to the other ports, directly accessing your network.