It should come with default settings that are listed in the manual and you should not really need to change them except to select WPA2 security and select a passkey (write it down you will need it for all your attached devices). Best to use the Ethernet port to connect to a computer to configure it and not mess with all the USB driver crap. The default configuration page address is 192.168.1.1, user = admin, and PW = password. I would also change the router login and password when you are I think that it makes you change the password -- again write that down and save it for later use. And don't use the simple or push button methods -- also turn off WPS if it is on to reduce the chance of Reaver attacks to back door your otherwise very secure WPA2.
The configuration pages are pretty easy to navigate.
7500 is an okay dsl modem/router, if it is what you already have it's fine for now.