If you bought one of the VG functional antennas, all you have to do is unscrew the whip of your factory antenna. The base stays on the car. Then use one of the screws included with the shark fin and attach the ring connector on the shark fin wire to the factory base. Then you just line everything up, pull off the paper from the tape and stick it down. Voila!
Lining the shark fin up is what takes the most time, I took measurements and then put some masking tape on the roof to outline where I wanted the shark fin to be. If I had to do it again I would cut out a template of the thing and tape that down to be sure I got it just right.