How do I find the IP address (Internet Protocol address) of a Windows computer?

Click Start  > Run... and type  cmd in the Open dialogue box.  Click OK

This will bring up a black window with a command prompt as follows:

Click on this window and type the following at the C:> prompt
ipconfig -all and hit the return key

This will display your network information.  
Look under the section entitled Ethernet adapter Local Area Connection: to find your IP Address