To use Robo 3T (formerly Robomongo) to back up your MongoDB dup your Database, you can follow these steps: 

1. Install Robo 3T: Download and install the Robo 3T software from the official website (https://robomongo.org/).
2. Launch Robo 3T: Open the Robo 3T application on your computer.
3. Connect to your MongoDB database: Click on "Create" to set up a new connection. Provide the necessary details like connection name, address, port, and authentication credentials (if applicable). Test the connection to ensure it's successful.
4. Select the database: Expand the connection in the left sidebar and choose the database you want to back up.
5. Choose the collection: Expand the database and select the collection(s) you want to back up. If you want to back up the entire database, skip this step.
6. Export data: Right-click on the selected collection(s) or the database itself and choose "Export Collection" or "Export Database" respectively.
7. Configure export options: In the export dialog, specify the export format (e.g., JSON, CSV, BSON) and the destination folder where the backup files will be saved. You can also choose to export data with or without the query filter.
8. Start the export process: Click on "Export" to initiate the backup process. Robo 3T will generate backup files based on your configuration and save them to the specified folder.
9. Verify the backup: Once the export process completes, navigate to the destination folder and verify that the backup files are created successfully.
10. By following these steps, you can utilize Robo 3T to back up your MongoDB database efficiently. Remember to schedule regular backups to ensure your data is protected and can be easily restored if needed.