You must first place another image from Image > Place or drag from another document, then click on layer with image (layer with image which you want behind) on LAYERS palette and drag it below layer with image to be above.
PHOTOSHOP
Photoshop is picture editor,what you mean?good picture editor?best free picture editors are GIMP and Picasa,i recommend to you Picasa
no
from filter menu
Adobe Photoshop CS5
You can use photoshop or another picture editing program to digitally edit the picture.
Photoshop can do this
Adobe Photoshop CS5
Open Photoshop, open your picture in Photoshop from File>Open, then start making changes. Of course if you are unfamiliar with Photoshop, you may want to learn the basics first.
photoshop
Find the picture and right mouse click on it select copy and then paste. Remember that Photoshop pictures when saved are defaulted to its own PSD file name. If you want another file type you must load the picture in Photoshop and then you must "save as" what ever picture type you want
All of them, the Macintosh computer was made for graphics and picture editing programs such as Adobe Photoshop.