How do i import video into iMovie from iPhoto? footage not recognized.

I am attempting to edit video in iMovie. I have either used an iphone4, iPhone5, or CanonPowershot to make the footage. It currently resides in iPhoto. i dragged & dropped, nothing. I exported the footage to a folder on my desktop, only 20% would import. I've searched forums & watched tutorial videos, can't find a solution Help, please!