Set up a catalog that lives in your own Google Drive.
Settings
Only needed while testing. In the finished app these are built in.
Import a spreadsheet
In Google Sheets: File › Download › Microsoft Excel (.xlsx). The
download carries your photos, which the Sheets API cannot read on its own. Excel and Numbers
files work too.
Which tabs to add
What's in the file
Match up the columns
Guessed from your headings. Change anything that looks wrong — nothing is
written until you press Import.
Preview
Your original spreadsheet is not touched. This creates a separate new one.