With RapidWiFi setting up a computer on our wireless system is a snap. The wireless system automaically provides all the addressing, gateways, and Domain Names Sevice (DNS) for your computer(s) via standard DHCP.
For Linux and MAC operating systems. Well if you use Linux and cannot seem to find where to setup up your networking at generally networking is contained in the "/etc/network" direcctory. Depending on your flavor of Linux there are only a few files in this directory. "networks" or possibly "if-up***" would be the files to look in to setup DHCP. Check the 'distro' "MAN" documents for your version of Linux to make sure what file(s) need to be changed and their location.
MAC users - you setup defaults to DHCP. If it doesn't then you'll have to go to 'Control Panels" find TCP/IP, select that option. Once there locate your adapter, select DHCP as the 'option' for you adapter. Say 'OK' and close your other desktops. You should now be able to connect to the Internet...