There are a couple of ways to add items to the inventory:
1. Via the import function when adding items in bulk
2. Via the "New" button on the top right corner of each collection index page. Clicking the new button will open a form showing the fields that were chosen to appear in that collection. This form can be populated and saved to create a new item.
*Note that non-admin users cannot delete inventory items created by others (but can update them).