How do I Private Message (PM) someone?

This are four ways to initiate a PM:  

1. Click the envelope icon at the top right of any page, then Compose New button.
2. From a thread, click a member's username or avatar to access their profile page, then click the Message button at the bottom middle of their cover photo.
3. If you don't want to leave a thread you are currently reading, rather than click on their username or avatar, simply hover the cursor over either one.  This will generate a popup window with summary profile information.  Click on Message in lower left corner of popup
4. Go to your inbox and click the Compose New button.