So you used the router's built in DHCP server. Now you are wondering how do I get an IP address from the router. The easiest way is to restart your computer. Here are some steps you can take to renew your IP address.

Windows 9x/ME

Go to Start, Run, and type "Winipcfg" (without quotes)

Select your NIC from the dropdown list and click Release then Renew.

Windows 2000

Go to the Command Prompt (Usually Start, Programs, Accessories)

At the prompt type "ipconfig" (no quotes)

Now to renew the adapter all you have to do is type the command "ipconfig /renew" (no quotes) at the prompt.