How to link a GPO to an OU?

1. Logon to the domain controller as an administrator.
2. Start Administrative tools Group policy management console.
3. Navigate to the desired OU, to which you want to link a GPO.
4. Right click on this OU and select Link an existing GPO; .
5. In the Select GPO; dialog under Group Policy Objects, select the GPO you want to link and click OK.

Choose the configurations you wish to modify, and save them.