DHCP stands for Dynamic Host Configuration Protocol.
Learn more.
Anyway, basically DHCP automatically obtains an IP address for your computer. If you
weren't using DHCP, then you would have to manually enter your IP, DNS, etc. If you're computer is trying to automatically "Obtain(ing) Network Address" (what you were getting stuck on), but your router did not have DHCP enabled, then you would be unable to obtain one. Often, routers have a limit on the number of DHCP clients (computers) that they want to hand out addresses to. This limit can usually be changed in the settings. (If you want a list of the clients, click on DHCP Client List under the
LAN Setup heading on the left side of the router settings).
To change your password or unsecure the network, go to "Channel and SSID" under the
Wireless heading on the left side of the router settings.
Do you have a firewall enabled on your computer? Temporarily disabling it and trying to reconnect may fix your problem. From there, you would just have to configure your firewall.
Hope this helps a bit.