How to Mass Create Metafields for Product Catalog

Bought this application thinking I would be able to add fields to shopify catalog.
Application only allows me to edit one at a time it seems?
Need to know if it is possible to edit all products at one time?
Are you able to add fields in excel?
Not understanding the use for the export/import system.
Any response would be appreciated.
Sincerely,

Curious George