If the gateway is locked to specific MAC numbers (all WiFi devices have such numbers), you'll need to have that. You can find your iPod's MAC number in Settings > General > About and Wi-Fi Address (I'm looking on my iPhone 5 running iOS 6, so it may not be exactly there; I think it is).
But before messing with the gateway ... on your iPod Touch, go to Settings and tap on Wi-Fi. Make sure Wi-Fi is ON and you should have a network shown under Choose a Network. Tap the name of the network rather than the arrow at its right side. That should give you the easy page to enter the kind of security and password. Tapping the arrow gets you a more involved page that looks scary. Hopefully you can avoid it. The easy one should work.
I'm moving your post to the home networking part of the forum for more visibility and trouble-shooting if you have more questions.