Follow the steps mentioned below to take a backup of SQL Server Database using Management Studio.
STEP 1: Open your Microsoft SQL Server Management Studio, whichever you select, standard or express edition.
STEP 2: Using your Database Username and Password, just login to your MS SQL server database.
STEP 3: Select the database >> Right-click >> Tasks >> Back Up:

The following Backup Database window will appear after you click on the “Backup“.

STEP 4: Select the following options:
- Backup type: Full
- Under Destination, in the Backup to check Disk.
STEP 5: Now, by clicking on the “Add” button to select the destination path and file name for the database backup file. You can change the destination path what you want to save:

STEP 6: Select the destination folder for the backup file and enter the “File name” with .bak extension:

Ensure you put your SQL database .bak file under the MSSQL backup folder.
STEP 7: Click the OK button to finish the backup process of your MS SQL Server Database. You will see the confirmation window with a message “The backup of database ‘SQLDatabaseName’ completed successfully“.

Take a look at how to Restore MS SQL Server Database Backup File