help creating user in Azure SQL

Job ID: 32129209

Budget: $10 – $20 USD

When I create a user it works. When I try to assign the run the query
EXEC sp_addrolemember 'db_datareader', 'user1';

I get this error:
Msg 15151, Level 16, State 1, Line 1
Cannot alter the role 'db_datareader', because it does not exist or you do not have permission.

I am the admin of the server and I see the role on the server.

Looking for an Azure wiz to help me out.
Related categories: SQL Azure Database Administration