You need to select File > Import > Artwork.
I assume you are aware these are gerber files, I've never seen gerber imported successfully into an ECAD system, good luck!
I use a gerber viewer called GCPrevue - you'll be able to look at the data with a viewer, take measurements & print out the layers but you won't be able to manipulate the data, you 'll need a gerber editor like CAM350 to do that.