I am assuming you have put a colour or a gradient colour as your background. On the tool bar select the circle (top left) draw the shape you require from the menu (the different shapes are chosen by right clicking at the bottom right corner of the circle shape box Then select the move tool (next one across from the circle ) and you should be able to move the shape
If you want to copy rather than move, choose the selection tool (Rectangle, Freeform, or Magic Wand), select the area you want to copy and hit Ctrl+C, then Ctrl+E, move the shape to where you want it, and click with the left mouse button to paste it.