How to grant Server level permissions to login in SQL Server

To grant Server level permissions to login in SQL Server (in this example the ‘CONTROL SERVER’ permission):
In SQL Server Management Studio:
Right-click on a SQL Server Instance in Object Explorer -> choose Properties -> Permissions:

Choose a login to which you are granting the permission, check the ‘Grant’ (or ‘With Grant’) box next to the permission, and click OK.
To grant “CONTROL SERVER” rights to login “LGN_test” you can issue the following command:
USE master;
GRANT CONTROL SERVER TO LGN_test;
GO
To grant “CONTROL SERVER” rights to login “LGN_test” with the right to grant “CONTROL SERVER” to other logins:

USE master;
GRANT CONTROL SERVER TO LGN_test WITH GRANT OPTION;
GO