how can I schedule daily backup at 9:00pm in SQL server 2008?
Use Microsoft SQL Server Management Studio to create a new Maintenance Plan.
In the object explorer go to the folder Management > Maintenance Plans.
This will open the designer.
In the Toolbox you will find a task named Back Up Database Task, drag this onto the designer.
Right click 'Back Up Database Task' select edit from the context menu
Backup type:
Right click the task to select the databases to backup.
Change the schedule of your maintenance plan to set when it will run.