Hi I've just downloaded Basecamp and all i can see on the map are the main roads. Is there a setting for seeing the street names or do i have buy a map??
You need maps. If you've got a compatible GPS receiver, you can connect the unit and display the installed maps. You can purchase maps from Garmin or you can do a google search on "OSM maps".
It should appear once you connct your nuvi and the nuvi is recognised. Note that the first time you do this it may take a while for BC to be able to view the map, after the first time it will be much quicker :)