Already got EAN-Numbers for your items? Simply go to product → Variants → quick edit and add EAN. Or create an import file with the EAN numbers. 

This video will focus on auto-generating EAN numbers. 

First of all, you have to set up your GS1-Settings. 
Settings → Miscellaneous → EAN-13 generation. 
 

GS1-Code and Manufacturer code is something you buy from GS1 - So the first 7 numbers are fixed. 

The next product reference number means the next 5 numbers in the EAN - Here you have to figure out which EAN number is the latest one in your collection. For example, if you got 20660 EAN numbers the next number should be 20661. 
If you got problems finding these contact TRAEDE support team. 

When all these are filled out - Press save and go to your product → Variants → “Generate missing EAN numbers” 
Now TRAEDE has auto-generated EAN numbers for the variants and you are good to go. When you add further variants, TRAEDE will ask if it should auto-generate EAN numbers.