Groups in ThruText have 3 standard fields: First name, last name, and phone number. All groups must have these fields, meaning any CSV you upload to create a group must also have these fields. If your CSV only has first name and phone number, you will need to add a column called last name and enter some value (e.g., Null) into each row for that field.
When you upload your CSV, ThruText will "guess" which column in your CSV should be associated with which standard field, and then will "map" those columns to the standard fields in the ThruText database. Here's what that looks like:
If you think that ThruText guessed incorrectly you can change the mapping using the pulldown menus under each header name.