I don’t know what an ‘olive’ router is but here is the first-time connection procedure:

First of all, make sure you have connected the computer to the router by Ethernet cable so that you can access the router’s set up details. This is done in a home network by typing 192.168.x.y into a browser’s Address bar. The values of x and y depend upon the make of router. If you don’t know the values, open a Run window (Windows Logo key+R), type cmd /k ipconfig (note the two spaces), press Enter, make a note of the Default Gateway address and type it into the browser’s Address bar. When asked for the user name and password, type the default values (if they are not known, look in the router’s user manual). Go through the sections until you find one where you can enter your ISP details, i.e. the user name and password given to you by your ISP. You should not connect to the internet.

Your router may have a section that allows you to backup and restore its configuration details. If so, make a backup to enable you to easily restore the set up in the event of having to reset the router to factory settings.