If Google Groups isn't available in your work or school account, ask your administrator to turn on Groups for Business. 
Group owners and managers can enter a welcome message for people viewing a group. A welcome message can:
- Help prospective members understand the group’s purpose.
- Show important information, such as your team’s website or email address, so co-workers know how to learn more about your team.
- Remind people of any important message, such as posting guidelines you’d like them to follow.
The message appears below the group name on the group’s conversation list.
Add or edit a welcome message
- Sign in to Google Groups.
- Click the name of a group.
- On the left, click Group settings.
- In the Welcome message field, enter, edit, or delete your message text.
- Click Save changes.