SQL Server role and manual admin

I had to create a fresh instance of database for work and had to assign roles. However, I didn't want to use the "click, click, click" method but rather like to type on the query window.

NOTE: This is to be done after you've created a Database and I won't go into details as to how to create a Database or how to add a user to the database.

I retrieve info from MSDN TechNetabout the database roles and are as such.

Database-level role name	Description
db_owner	Members of the db_owner fixed database role can perform all configuration and maintenance activities on the database, and can also drop the database.
db_securityadmin	Members of the db_securityadmin fixed database role can modify role membership and manage permissions. Adding principals to this role could enable unintended privilege escalation.
db_accessadmin	Members of the db_accessadmin fixed database role can add or remove access to the database for Windows logins, Windows groups, and SQL Server logins.
db_backupoperator	Members of the db_backupoperator fixed database role can back up the database.
db_ddladmin	Members of the db_ddladmin fixed database role can run any Data Definition Language (DDL) command in a database.
db_datawriter	Members of the db_datawriter fixed database role can add, delete, or change data in all user tables.
db_datareader	Members of the db_datareader fixed database role can read all data from all user tables.
db_denydatawriter	Members of the db_denydatawriter fixed database role cannot add, modify, or delete any data in the user tables within a database.
db_denydatareader	Members of the db_denydatareader fixed database role cannot read any data in the user tables within a database.