Selecting and Filling Transparent Portions of an Image
Photoshop CS6 (will work on some previous versions of CS and Elements)

  1. Layer -- Merge Visible
  2. Select -- Load Selection -- layer name Transparency (this will select all of the image that is not transparent)
  3. Select -- Inverse (this will make the transparent portion of the image selected.)
  4. Select - Modify - Expand - 10 pixels (this will prevent edges showing in the final result.  5-20 pixels will work depending on your file size)
  5. Edit - Fill   In the diaoge box set Use: Content-Aware , Mode: Normal, Opacity: 100%, uncheck "Preserve Transparency.
  6. Press "Control - D" to remove the selection.
This can be made into an action in Photoshop.  The action can then be moved to the later versions of Elements.  If the process does not work perfectly you may "fix" the defective areas using the clone stamp tool, content-aware fill, healling or the brush tool.  It may be necessare to crop out the offending areas.