There are two ways to mark a resource as important on Mindstone.
1. When saving a resource with the Mindstone extension, simply click the 'Mark as Starred ★' button on the pop-up in order to 'star' that resource.
2. If a resource has already been saved to Mindstone, then from your Inbox, click the ☆ icon underneath the item in order to 'star' it.
Once a resource has been starred, it will be prioritised when you're ranking your resources by importance, and you'll also be able to access it from the 'Starred' view in your Inbox.