Password protected entry to main page?

So I’ve been able to successfully create a sort of Landing page on my website, but I was wondering if anyone could help me out with the following:

I intended on adding a sort of password protected entry button of some sort on the landing page, linking to the main page (home page).

So basically on the landing page, it would ask to type down a password and once typed down and entered, it would take you to the home page, is what I’m trying to accomplish

The current landing page is more of a Welcome page and a sort of introduction before entering the actual home page

I’d be grateful if anyone could help me out with this, thank you kindly!

Regards,
Russ