If your customers are already in a database like excel just save it as a .CSV file and you are ready to move to the next step.  If you are currently using a program like Quickbooks or Clip you can export your existing customers within your current software.  Export all of the columns, when you import the file to Obex you will be able to choose the ones you want.

Once you have your list exported simply go to Settings  >  Import Customers  >  Choose File.   Locate your .CSV file, press open, and tap Show Me The Conversion.  Your .CSV will begin to populate in Obex and you will be able to select which columns that you want included in the Customer Profiles.  When that is done your customer information is now ready for use.