Newbie trying to import subcategories

[Drahnyn]

I downloaded the categories_import.csv from the Advanced Parameters/Import menu. I put my info there, following that, and when I import nothing happens. Well, actually, while I'm working at the website I'm at an https, but when I click Next Step, the next page goes to a http address (same site otherwise) and gives the message 
The information you’re about to submit is not secure
Because this form is being submitted using a connection that’s not secure, your information will be visible to others.
categories_import - Copy.csv

Ignoring the https/http issue, I'm guessing that I've got a simple thing incorrect but I cannot [obviously] figure it out.

[Mr Rick]

Can you tell us the version of your PrestaShop?

[Drahnyn]

 

1.7.8.0