When students log in, show them where they can go to find out more. There is a "Student help & resources" page under their name in the top right corner of the site. As a teacher, you can also see this page under your own initials.
The Student Guide is worth their time to have a look at and is excellent for parents too. It contains video guides on the key features of HegartyMaths.
As you can see, there are other resources that there may find helpful too.