Welcome to the Help Forums.
I'll start by suggesting that you read the Posting Guidelines. You can find them near the upper right of nearly every Help Forum page.
We need more info. For example, I could say "Log into your router and look it up". But I don't know if you actually have one.
I could also say, "If you are already using a wireless device to connect to a router, then you can find the info by looking up the SSID on that device's connection properties." But again, I'm forced to do guesswork.
I would prefer not to.
Thanks, in advance, for providing more details.
Couple of ways.
The SSID is the Name of your Router that you gave it to distinguish it from other routers in the neighborhood.
If you did not change the SSID when you set up the Encryption to keep your router from being used by pornographers then the default ssid is probably the same as the brand of the router (Netgear for netgear routers etc)
If you have a wireless laptop, look at the Wireless Icon on bottom right of your Windows Screen. It wll show the SSID.
If you don't have a wireless laptop connected up, use a computer connected by ethernet able to the router . Open up your browser and type the Router IP address into the Browser Address bar and hit enter
The IP address is usually 192.168.1.1 but can be 192.168.0.1 or 10.0.0.1
Once into the router navigate to the wireless encryption tab and you will see the SSID there.
I love it when nothing suppresses the will to guess what's happening. Or since I provided a few partial clues, did you feel compelled to fill in some more "blanks"? I did get a kick out of the "pornographers" line, as if that's the only thing someone might hijack a network connection for.