Create a new Page, go to the Page Builder tab and assign the template Membership Page –> Member Blog Page. This only needs to be done once and is now your members blog homepage. This page can now be added to your nav menu
IMPORTANT: To wrote blog posts for the members blog, you need to navigate to MemberPosts in the left sidebar, NOT the normal Posts tab. Write your blog posts as normal in here and they will only appear in the members blog.
The MemberPosts blog area functions exactly the same as the normal blog posting functionality, with the exception of only appearing in the members blog.