Creating computer-to-computer ("ad hoc") WiFi network directly from your computer, without any router.

Mac OS X

On your Mac computer click on WiFi antenna logo in menu bar (at the top right corner of the screen) and select Create Network... from the drop-down menu:
 
     
 
(if you don't see the WiFi antenna logo in menu bar, you may want to run the System Preferences app, open the Network tab, select your wireless adapter there and find an option to show your WiFi adapter status in menu bar)
 
The Create a Computer-to-Computer network dialog will appear. Make up a name for your network and enter it in the Name field. Check the Require Password checkbox. Select 128-bit WEP in the Security drop-down box. Make up a password consisting of 13 ASCII characters (this is important!!!) and enter it in the Password and Verify fields. Do NOT use a password consisting of 26 hex digits, regardless of what the dialog suggests. The dialog should now look like this:
 
     
 
Press OK. Note how the WiFi antenna logo in menu bar changes to reflect the fact that your Mac now is hosting its own computer-to-computer network, instead of being connected to a network hosted by somebody else:
 
     
 
Please note that if your computer was connected to Internet via WiFi (via a WiFi router or via some public access point), you will loose this connection after creating your own computer-to-computer network, because your computer can't host a WiFi network and be connected to another WiFi network at the same time using the same WiFi card. So if this is the case, you may want to reconnect to that other WiFi network that you were using to access the Internet after you're done transferring files to GoodReader.