how to embed import option in the form to upload the details instead of filling online.

Are you trying to import data from a CSV(.csv) file or Excel(.xls) file to your form submissions?

If that's the case, then I would suggest you use this tool: http://import.jotform.io/

Here's a guide that may help you import your data

Import-App-Easily-import-your-Excel-or-CSV-data-into-JotForm