For most cases, our spreadsheet will recognize all the columns in the spreadsheet immediately if you go to Settings > Scan DB. This action will show all the metafields represented as columns. In the case that for some reason the field that you want to show is not picked up by the spreadsheet, you can create the column manually.
To create a new column, go to advanced settings > add columns for custom fields.
Once there, you’ll have to specify the values for the new column: name, key, type.