You can paste a cut or copied selection into an existing layer.
To paste a cut or copied selection into a layer:
On the Layer palette of the target image, click the layer into which you want to paste the selection.
Choose Edit > Paste and choose one of these commands:
Paste As New Selection (Ctrl + E) Pastes the contents of the clipboard as a floating selection above the current layer. If the image already contains a floating selection, it is defloated first.
Paste As Transparent Selection (Ctrl + Shift + E) Use this command to remove a specific color from the selection you are pasting. The command makes transparent any pixels in the clipboard data that exactly match the current background color (in the Materials palette). Then the command pastes the contents of the clipboard as a floating selection above the current layer.
Note: Select the background color before you paste.
Paste Into Selection (Ctrl + Shift + L) Pastes the contents of the clipboard into the current selection. The clipboard contents are resized to fit the current selection.
Copying One Image into Another Using the Browser
Copying Paint Shop Pro Images into Other Applications