Import contacts CSV

in my excel csv file I have like 800 customers, and then several columns with specific tags that apply to that customer, so column is market with an “x” if that customer is related to that tag.
I created these tags in the emclient, but then I didn´t see how to create specific columns in the spreadsheet as to import the file and use these tags already there.
or better, how to create new columns in the emclient spreadsheet list of customers ? or those columns are fixed and I can´t create new ones ?
main problem is that with 800 contacts and then add all but later having to go one-by-one adding each tag for that customer would take quite a long time.

You will need to have a single tag column in the csv file, with the name of the tag in that column. That means only one tag per contact when importing from CSV.

Then when you import the csv file, map that column to tag.

You can’t add custom fields to a contact.