I'm guessing the map card in the 8? Navionics card? If it's in the 8 and both units are on go to the chart page on the 7. At the top right of the screen press "Menu", near the bottom of the drop down menu press "chart options". A sub menu will appear at the very bottom of it should be "change to Navionics".

The waypoints should automatically transfer when both units are on. I don't recall if it will prompt you or not. Go into the device list on each unit and make sure one is showing up on the other.