After uploading your guest list, you will be instructed to match the fields on your imported guest list with existing Boomset fields. If a box is red, this means the fields are not matched, and will therefore not be uploaded. Simply click the settings gear and select an option from the drop-down menu that best correlates with your field. If need be, you can also categorize your field as a New Custom Question or a New Session through the drop-down menu.
Be sure to save your selection.