You must have the game installed, version 1.8.9
How can I check this? When you launch the launcher, the version of the game is shown in the lower right. If it is a different version, you should change the current profile (bottom left) and select version 1.8.8
Click the PLAY button, wait for the Minecraft game to load.
Choose: Multiplayer
Click the “Direct Connection” button or, if you want to save the server in your list, click “Add Server”
In the field “Server address” write: citywiese.eu:25565
CityWiese.eu