1. Open the main picture file (A)
2. Open picture file B. Use one of the selection tools, e.g. lasso tool, or magnetic lasso tool, to select the object/person. When the seletion is complete, press CTRL+C on the keyboard to place it on the clipboard. Go back to A, and press CTRL+V. You should see 2 layers in the layer palette: Background layer (A) and the layer with the selection above this.
3. Activate the move tool to position the selected object.
4. Repeat with C, D, E, etc.
If you wish to to place several pictures in their entirety on one canvas, you have to do the math so that they will fit. Once you have determined this, go to File>New>Blank file, enter the dimensions (H&W) for the canvas. Next, go to File>Place and point to each picture that you wish to place on the canvas, Each picture will come in on a separate layer, and you can position them to suit.
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