Addressing images

[Jim Hurley]

(Somehow this message was garbled in the previous  post. I just sent 
it to myself, and it seems OK.  Trying again.)

I've discovered I don't know the first thing about addressing images.

Suppose I have created two images, "myFIrstImage" and "mySecondImage."

The rect of each is set to the screenRect

How do I select the image which the next drag command applies to, that is

choose the pencil tool
drag from 100,100 to 200,200

If this were a graphic, I could address the graphic by name, that is

Set the points of graphic "myGraphic" to ........

Or suppose I have an imported jpg and a blank image "myBlankImage", 
how do I direct the drag command to "myBlankImage" and not to the jpg?

Jim