The Sidebar is a fast way to:
Access Help from the Sidebar Quick Start menu.
Open recent documents from the Sidebar Open menu.
Resize an image from the Sidebar Size menu
To resize an image from the Sidebar:
Select the image
Go to the Size menu and click on the Size you want to apply.
The image is resized as you have indicated.
ALTERNATELY, you can drag an image directly from the browser pane onto a size. The image will be added at the desired size.
To view the Sidebar, go to the View menu and select Sidebar. The Sidebar
displays. Repeating this hides the Sidebar.