You have to make sure that your software supports WebDAV protocol. If it's not built into your system, you may use standalone client software, like AnyClient, which is free (at the moment of writing this) platform-independent Java-based client application.
Connecting your iPhone to your computer:
- connect both your iPhone and desktop computer to the same WiFi-network
- start GoodReader, open the WiFi-transfer page (keep it open all the time). Make sure that the WiFi-transfer page shows that WiFi-connection is present and you see valid IP-address. If you don't see it, you're not connected to a WiFi-network.
- use appropriate software to transfer your files using the IP-address
- only when you're completely done with file transfer, close the WiFi-transfer page
- please do NOT assume that the IP-address is the same as it was when you were connecting the last time - IP-addresses change periodically, check it every time