The New button on the Project tab of the Project Editor allows you to add Products or Labor Items that do not exist in your Catalog to the Project. You can also add Miscellaneous Items to a Project.
An appropriate form will open based on your choice of Product or Labor:
Manufacturer, Model, and Category are required fields for Products or Labor Items, everything else is optional. What fields you fill in for an item will depend on you. Click the following links for full details of the fields for Products and Labor Items.
When you add a new Product or a Labor Item in a Project, it does not exist in your Catalog. If you wish to add the new item to your Catalog, use the Update To Catalog feature.