If using Mobile Web (not the app), click HERE
If using the App, click HERE
When someone sends you a private message you will see a small number above your messaging envelope. You can reply to your private messages like this...
1. Log into your account.
2. Click your messaging envelope in the black bar across the top of the site.
3. Click on the subject line in the private message sent to you.
4. Type your message in the white box. Add a pic or a link if you'd like to. Click "Send Reply".
5. Once you've sent your message, you will see the full conversation.
Now that you know how to reply to a private message, head over to the site and give it a try by clicking HERE.