Once you've upgraded to the Community Builder or Business Plan, you can add a Welcome Section to the top of your feed that all new members will see.
The Welcome Section can include an unlimited number of pinned posts — including polls, articles, questions and events — and is displayed at the top of the activity feed for new members. It can also be one of the sections that all members see in Search and Discovery when they open up search.
To feature (or pin) a post to your Welcome Section, just navigate directly to the post you want to feature when you're on the web. Click on the three dot menu in the upper right corner and follow the prompt that says "Add This To..."
From here, you'll see the option to add the post to either your Welcome Section or your Featured Section.
To rearrange the order in which posts appear in your Welcome Section, go to Host Management > Content > Welcome Section. From there, just drag and drop to re-order posts.
Or, remove a pinned post from your Welcome Section by tapping on the option to "Unpin" the post.
Going forward, all new members will see your Welcome Section right at the top of the feed after they join.