Adding anchor links in Squarespace 7.1 - no index page option

HI,

I'm struggling with getting used to squarespace 7.1 trying to do simple things.  Previously in 7.0 you can create index pages and link to the page slug. 

I am create a one page scrolling website, but I wan to create a link in the navigation to jump to a section further down the page.  How on earth do I do this in 7.1??

many thanks