In case you have never installed Snapper before, you will have to reload the current page to make the extension work.
When you want to make a screenshot, click on the small picture frame icon in the Safari toolbar, somewhere between the back/forward buttons in the address bar.
When the button is clicked, a black rectangle appears on the top right of the Safari content. There, you can see a thumbnail of the screenshot which you can drag on your desktop. Close the orange button when you are finished.
The toolbar icon is disabled if Safari shows an empty page or if the extension is currently showing a snapshot to be dragged away.
Note: Due to the current Safari limitations, the Snapper extension does not allow you to make snapshots to whole pages or to name the resulted snapshot image.
