iPhoto move problem

Hi all firstly would like to say hello (newbie)
I have a problem using iPhoto 11. I Have a 27" iMac 2010 and a G force 2tb external hard drive.
My iMac hard drive is about 3/4 full. The system I require is to use the G drive only! As the main source for my iPhoto library. I have managed to transfer the libraries over to the G drive. The system I used was finder, I opened up two windows, then dropped and dragged each library one at a time. And managed to confirm they are in place on the G drive. However when I delete them on the macs hard drive they also delete on the G drive. I have also tried turning off the G drive before deleting on the macs drive. But when I return power to the G drive and the mac see' s the G drive they are deleted on the G drive. Please help I am getting very frustrated. Also when replying please try to be as least technical as possible as I am the wrong side of pensionable to grasp computer jargon.
Regards. Mike

 

Hi thanks for replying drag and drop using finder
Regards mike