There are several ways to start a one-on-one Conversation with someone:
In your Contacts list, next to the person, click . (If you don't see the person you want in this list, see How do I follow people or add contacts?)
On your Contacts page, next to the person, click One-on-One.
In an item's membership bar, click the person's profile picture, then click Open One-on-One.
Anywhere else you see a person's name or picture, click it to open their profile. At the top of their profile, click One-on-One.
One-on-one Conversations automatically open in a minimized view at the bottom of your screen.
To view the one-on-one Conversation in the main window, click
To hide minimized view, click in the banner. The view collapses and the banner turns gray. If your partner posts to you, the banner turns blue again. Click the banner to re-display minimized view.
To close the minimized view, click in the banner.