It is easy to insert ready-made shapes into your page.

Select the Shapes Tool. As you do so, the toolbar expands to show you all the shapes from which you can choose.

Once you have made your selection, click and drag on your page to "draw" the shape.

Try a few.

You can create a shadow for your shape by copying it (right-click) and dragging the one on top of the other, off-setting them a bit. Send the shadow shape to the back (Send to Back button) and colour it with a contrasting colour.