Support is getting a string of emails from people who are finding it difficult to post questions in Google Groups because of the changes Google have made
Here are some brief instructions
You can only post in the groups if you are in desktop mode so I am basing my description on posting from a phone because a PC is more straightforward
To post you need to be in "Desktop site" so choose that option from your browser's menu
To reply to an existing message, use the reply arrow
To create a new topic, use the "menu" icon followed by the "New conversation" button