Hi, I am new at this how to start up a forum. Hope you can help me with this. I want a topic that is always stay at the top of a forum. How do I do this. Same as the picture. 

You can pin a topic to keep it at top. You can find this action either inside the Moderation Actions menu while viewing a topic, or you can select the topic on the forum page and use the Moderation Bar to pin it.

Thank you Daniel for your help.