Overlaying an image of a video in Premiere is a very simple process. Once both the video and image are imported into Premiere, drag both of them into the timeline. To make the image overlay on the video, make sure the image is on a higher video layer. Picture in picture is done with the same method, but using a video clip in replacement of an image.
For a tutorial on basic editing, click the playlist below.
Lynda Playlist: DLL Adobe Premiere Basic Editing: