You have to get the password and security setting for the router first, if you don't have that, you need to clear the passwords and start over. Download the router manual from the manufacturer to learn all the settings, and how to change them. You can clear the passwords and set new ones.
Without control over the router, you have little chance of connecting. You need to know the network name (SSID) so you can connect to the right router.
(your neighbors routers will also be detected, but you are locked out)
Look in the lower right hand of the desktop, click on the communications icon, is there a list of available networks?
click on the network you wish to connect to, (that's why you NEED the name FIRST), enter the password when prompted.