Two wireless networks, one completely wireless, the other wired and wireless. I want to join the two networks so that I can move files from one to the other and vice versa. How do I do this, please

You'll need a router, and eacdh network should have a different set of IP addresses. Cisco routers have the ability to have more than one SSID, so you may want to look into that.

Note: A standard home DSL/Cable router probably won't work, unless you can change it from Gateway mode (which uses NAT) to Router mode (which DOESN'T use NAT)