How to password protect page without access to properties editor?

Firstly, all I want to do is password protect a page on my website. I looked up how to do that and the help center said to click on the background of the page to access the background properties editor. I tried doing that and nothing appears. I have no access to the properties editor. Then I thought maybe it was because I was using sitebuilder plus so I downloaded 2 different versions of the sitebuilder desktop and neither of them would let me open them. They both said I can only edit my site from sitebuilder plus. Can someone please fix this issue for me? I am becoming very frustrated with all the glitches from homestead web builder, especially considering how much I pay every month for the service.