To get in touch with other users, you can write messages. To do so, click on the speech bubble at the top right and select the plus sign (marked red in the graphic):
In the next screen, the message title, recipient and the actual message must be entered. Click on "Send" to send the message via the PFF. The user receives a notification via the PFF that he has received a new message.
Sending a message via the user profile
The second way to send a message is via the user profile. To do this, click on the user name of the user who is to receive a message. The user profile opens. Go to the following menu and select "Start conversation":