I'm very happy to have found this plugin, but I need it for a very simple situation and am finding it quite confusing. This is for a snowmobile trail condition report site. All I need to do is assign certain users to be able to update certain pages. For instance, John needs to be able to update the trail conditions for the page called Anytown and Mary needs to update the page called Hometown. All I want them to see when they log in is their particular page and have the capability to edit it, upload a photo or two, and that's it.

Is there someone who can walk me through the steps? I don't understand how the default groups work (Contributor, Editor, etc.) as opposed to creating my own group. I would appreciate any pointers. Thanks!

Your question is answered here.

Make sure those users are not WordPress Editors. You may also need to adjust this setting:

Roles > Options > Features tab > Content Maintenance > "Roles and Restrictions can be set:"