
Explanation:

Step 1, Step 2:
First you need to create a login for SQL Azure, it's syntax is as follows:
CREATE LOGIN username WITH password='password';
This command needs to run in master db. Only afterwards can you run commands to create a user in the database.
Step 3:
Users are created per database and are associated with logins. You must be connected to the database in where you want to create the user. In most cases, this is not the master database. Here is some sample Transact-SQL that creates a user:
CREATE USER readonlyuser FROM LOGIN readonlylogin;
References:https://azure.microsoft.com/en-us/blog/adding-users-to-your-sql-azure- database/