In order for Syncopotamus to recognize the fields in your Google Sheet, you need to do two things. Don't worry, they're easy.
1. Have a header
The top of each column needs to have the name of a field. This is what Syncopotamus will use to fill the cards, and put them in the right place.
Header
2. The rows up to the header must be frozen
Syncopotamus uses the frozen row to know where the header ends and the data starts.
You can have as many frozen rows as you need. Syncopotamus will ignore them all. It will only use the last frozen as the header to know what data is in each column. All the rows that are not frozen will be used as the data.
Frozen rows
If you've never frozen rows before, it probably looks more complicated than it actually is, as you'll see...
Freezing the rows
Place place the cursor on the header row
Click View menu
Select Freeze
Select Up to row X (where X is the row of your header)
Steps to freeze row
And that's it! You can now create Card Table cards from this sheet, and vice-versa!