Go to a users page, and click follow. That's it! Updates from that user will now show up in your wall feed, visible by pressing the Z-icon in the top left corner, and in your Activity feed, accessible from the menu in the top right, second from right. Blocking a user prevents that user from interacting with you.

Your Activity feed is available from the menu, top right corner, second item from right. When a user you follow interacts with other users, messages you or does other things of interest, you will get notified here.

By selecting Conversations from the top right Actions menu, you can chat with users you follow. Select a contact from the profile icon list. If it's too long, just narrow it down by typing in the first few characters of the users name in the search field. To view an existing previous conversation, select it from the bottom list. When a user writes to you, you will be notified in the Activity feed.

By hovering over an item, a list of possible actions become available. On the left side, the D opens up comments for the item, while the arrow item copies a shareable link to the item to clipboard, suitable for sharing on other platforms. The right side ❤️ allows you to like or unlike the item, while the + lets you copy the item to your own boards (for free content only, premium for-pay content cannot be copied).