Not too familiar with elements but if you find the folder the images are located in (i would guess they are in your 'my documents' folder if you use a pc) then select all the images, right click then copy.
Open up the flash pen and then right click the open space in the window and then click paste, all the images should appear.
There are plenty of other ways to do this which I am sure other members will tell you but in my opinion if your not too technical then this should be the easiest.
Cheers