When you are importing a list of objects/entities (eg. participants, contacts, organizations, etc.), you must first make sure that corresponding fields have previously been created either in the Global or Event field manager (such as: First name, last name, position, country, etc.)
If you are uploading a list of participants with the following fields: First name, Last name, Email, and Position - during the import process the system will try to match those fields with existing fields in Azavista's Field Managers.
If these fields do not exist, you won't be able to match them, i.e. find them in the field's dropdown list as seen on the screenshot below.
To prevent this from happening, make sure all of the fields you want to include already exist in the Field Managers.