After setting up Family Sharing in Mac, You now have to add a family members info. Follow the below steps
1. Go to System Preferences > I Cloud and click On Manage Family.
2. Click on Add Family Member.
3. Now enter the e-mail address of the desired family member and click Continue.
4. Now enter 3 digit CVV Security code of your Payment card linked with your account to confirm that you are the family organizer. This step is crucial for authentication purposes. Click continue.
5. Enter you Apple id password to continue. Click continue.
Now, It’s a two-step process for the obvious security reasons. So the family member to whom you have recently added will get an e-mail invitation in Mail and Alert in I CLOUD on his/her Apple device. Following are the simple steps to accept the invitation.
1.Go to Settings
2. Tap I CLOUD > Invitations
3. Tap Accept. Than tap on Confirm and Continue.
4. Agree to Terms and Conditions.
And you are Set.