There is a lot to know about networking in general and wireless networking in particular. So, I've put together a bibliography with articles and videos you can watch to learn more about the overall topic and/or a few specifics.
From CNET: Home networking: Everything you need to know
From KnowHow on the TWIT Network:
Networking 101 The whole series is helpful, but the episode on
Router WiFi Setup may be particularly helpful as that's what I referred to when setting up mine.
There are some interesting alternatives for setting up subnetworks for trusted, untrusted and perhaps totally untrustworthy devices using old routers. You might want to check out the Know How episode:
Networking 102 - Part 4: 3 Dumb Routers