You have not clearly told that whether you want to change the name of your computer or the IP address. In order to change computer name, you should right click on the 'My Computer' icon located on the desktop. Then go to the properties and then click the tab 'computer name', there you would click the tab 'change' in order to rename your computer. And in order to change the IP address you should let the network administrator know so that he or she can configure the IP on the domain as well.
