Whiplash will attempt to import newly created/updated Products in your store by default. However, sometimes you'd like to do a manual import, or just confirm that we've got the item correctly.
You can do that via Integrations→Import Items:
Here, you'll be able to see what's been imported and what hasn't. Imported items will be hyperlinked to Whiplash Items.
You can choose to import selected items, or all items.
Note: Import all items will import EVERY item in your store, not just the ones on the current page.