The backup command listed in the previous post will work for you.

Assuming you are running the Standard version of SQL Server and not the Express edition,

if you want a simple way to both backup and schedule the backup to occur every night, you should read up on maintenance plans.

In Sql Server Management studio, connect to your database intance.

On the menu bar, go to View, Object explorer.

This will show the server you are connected to.

Expand out Management, Maintenance Plans.

Right click on Maintenance plans, and choose Maintenance plan wizard.

Press Next and change change default plan name to be MP_BACKUP

Press Change and change the schedule to be DAILY.

Press OK

Press Next

On the Select maintenance tasks, choose to Back Up Database (Full)

Press Next

In the drop down, choose the radio button for ALL Databases and press OK.

In the folder text box, pick the drive and folder where you want the backups to go to

IMPORTANT: Pick the check box that says Verify Backup Integrity.

Press Next.

In the Select Report Options pane, choose where you want the log file to be created.

and press finish.

This will create a SQL Agent job that will run daily at the time you specified and create your backups.

It would be best after making a backup, to attempt to restore that backup file to another server to make sure it can be done.