In some cases, you might need to add information that's not present in your import feed yet; for example, setting the "age_group" for your products (adults, kids etc.). To do that you'll need to add a new field. You can add a new field by scrolling to the bottom of the mapping and clicking on '+ add new field'. It is recommended that you use a standard Channable field name, this makes it easier to set up Channels later on. Click on 'Custom' and select a field from the drop down menu. If you cannot find the field you desire you can click on custom again and choose a name.
Do you want to interactively learn about setting up your import in Channable? Learn how to create a Channacademy account in the Channable app through this Help Center article and start with the Basic Imports course.