Go to the New Scan page
Here pick your scanner device from the dropdown. It may take a few seconds to query all available scanner devices connected to your computer.
After you have selected a scanner device, the Preview button (if supported by your scanner!) and the Scan button become enabled. Now you can acquire a new scan simply by clicking the Scan button. The scan operation may take a few seconds. Or even a few minutes if you scan multiple pages when your scanner is a feeder.
After you’ve scanned the page (or the pages) don’t forget to provide a proper name, description and keywords to find your scanned document later quickly.
After you’ve done so click the Save button.
Pinned to TaskBar
When you’ve pinned Scan Archive to the TaskBar you can simply create a new scan by right-clicking on its icon and chose “Acquire new scan“: