|Ignore those who haven't tried recent versions of Norton, they are now very good programs as anyone who keeps up with the times will tell you....|
Anyway, I take it you have got 360 actually installed on the netbook? There will be a Norton icon in the system tray if you have, so double click that, make sure your are connected to the internet and then click on 'My Account', near top right - there should then be a prompt asking you to activate the product - click through that & you will need to input the activation code at some point.
If there's no icon present then you need to download the program first from the Norton website HERE for example (download the trial version, your key will make it into a full version) - make sure you have the key for the correct version (4.0 or 3.0).
"I've always been mad, I know I've been mad, like the most of us..."