Well, the name you are looking to change lives in one of two places (still not sure which one you are trying to change)
The name of the location profile on your iBook lives in System Preferences -> Network. You will see a dropdown box labelled "location. From that dropdown, you can choose "Edit locations" . When you do this, a little dialog will come up with all the location names set up on your iBook. Click the "Rename" button and it will allow you to rename your location name to whatever you like.
If you are talking about the Network Name of the wireless network, that lives in your router. You'll have to go into your router configuration page (which usually entails browsing to 192.xxx.xxx.xxx with a web browser. I'm not sure where the name is stored in a D-link router, in my Netgear wireless router, there is a place in the router config under "Wireless settings" where you set the name of the wireless network (also known as the SSID).
It's pretty much going to be in one of those two places.