Safari blank screen etc etc

I do need help on something that occurred about 2-3 weeks ago.

When I use my apple desktop that is currently  mac OS High Sierra (not mac OS Mojave) and click on Safari new private windows I get a blank page which states " Safari Can't Open the Page "www.apple.com" because Safari can't load any data from this location." This is permanently on that page.

When I click on a new window it is sometimes ok but shows up from time to time.

Any ideas why is is to showing this? Can it be rectified?

I recently had a software update and this blank page on private windows is still there.

Secondly when I do use Safari and google something many webpages have 'not secure' on the address. I tend to avoid them at all cost as they also do not have the https://. Should I be seriously worried.

If there's any solutions for these issues I would greatly appreciate if the response is in simple terms and not too technical. I am still navigating my way around my computer as there is so much to learn.