Import data

Hello, 

I am trying to update my customer information (add in their area, region and province - 3 columns). All the customers are already in my SAGE. I tried to import the csv file that contained all my updates, but it only wants to import all the headings into one column. I went ahead with this and it duplicated all my customers. 

So now, I need to remove the duplicate clients. But I'm also looking for a template of the csv file that can be imported into Sage - can I only import 1 column at a time?

Thank for your assistance. 

Janine