Select the “Chats” button in the lower function bar.
You can then select the relevant group chat or individual chat in the overview of the chats suggested to you.
Suggestion: You can also use the search bar to enter the name of the chat / person to find the relevant chat more quickly.
When you have selected your chat, you can click the link ...
... and send by clicking on the red arrow. This is then sent to all members who are part of this group.