1) Go to your Gmail contacts

2) Check the box on the left to select which contacts you would like to add to your Google Groups. Next go to the 3 vertical dots a dropdown box will appear and select “Export…”

3) A dialogue box will appear, and you will be prompted to choose which contacts, as well as which format they should be exported in. Choose the “Selected contacts” option, and the “Google CSV” format.

4) This will export them to a Microsoft Excel CSV (Comma Separated Value) document. Find and open this document (it should be in your downloads folder) and find the column which contains the email addresses for the exported contacts. Select the email address and copy them. You can copy them by right clicking and selected “Copy” or by (on Windows) Ctrl+C and (on Mac) Command+C.

5) Access your Google Groups

6) Click “My groups” on the left, and then click whichever group you want to add these contacts to.

7) Click the “Manage group” option on the bottom right.

8) Then on the left side of the screen click “Invite members."

9) You are then brought to a page where you can enter email addresses of people to invite. Click there and paste the email addresses into that section. You can paste by either right clicking and selecting “Paste” or by using (on Windows) Ctrl+V and (on Mac) Command+V. Once you have entered the emails, and written an invitation message to the recipients, click the blue “Send invites” button near the top of the screen.

SOURCE MATERIAL:

https://support.google.com/mail/answer/30970?hl=en

https://support.google.com/groups/answer/46398?hl=en