The "source rectangle is empty" message

I am a new Photoshop Elements 6 user.
Everytime I attempt to edit a photo I get the message "could not complete
the command because the source rectangle is empty". What are the steps I
need to follow to get a file into the "source rectangle" ?
What are the first steps to get a photo into the "source rectangle" ?
None of the photos that I select ever show up in the "source" box.
They always show up in the "final" box only.
I need help with the basic, initial steps to follow on how to get my photos into
Photoshop Elements 6. Thanks for your help.

Hi Carence,

Are you familiar with the concept of layers? It sounds like you are on a 
layer (imagine different layers of an onion) that does not have anything 
there to select.

Jim,
Tell the steps you performing? Also tell the information about file in the
same.