As of August 2014, Pinterest is the fourth largest social networking site on the web with an estimated 250 million monthly active users. With that many people using the site to browse and pin all sorts of stuff, it only makes sense that Pinterest would introduce a more direct way to contact, communicate and collaborate with other users that doesn't exclusively involve leaving them a public comment on one of their pins.

Everyone with a Pinterest account now has their own private inbox that they can use to privately send pins and text-based messages to other users. Here's how you can use yours -- both on the web and on mobile -- if you're not quite sure where to start.