Log in to your Smartsheet account and open the sheet you wish to export. Click on "File" in the menu, then select "Export" and choose "Export to Excel." This will download the sheet as an Excel file (.xlsx) to your local machine.

Open the downloaded Excel file and review the data to ensure it is clean and properly formatted. Remove any unnecessary columns or rows, and ensure that the column names are suitable for a database (e.g., no spaces or special characters). Save the cleaned data in a CSV format, which is compatible with Teradata.

Launch Teradata SQL Assistant (or another Teradata client like BTEQ) on your computer. If you haven't installed it, you can download it from the Teradata website. Connect to your Teradata database using your credentials and database connection details.

In Teradata SQL Assistant, write a SQL statement to create a table that matches the structure of your CSV data. Define the appropriate data types for each column to ensure that the data will load correctly. Execute the SQL statement to create the table in your Teradata database.

Use the Teradata FastLoad utility to load the CSV file into the newly created table. Open the command line interface on your computer, navigate to the directory containing your CSV file, and enter a FastLoad script similar to the following:

```
.LOGON your_teradata_server/username,password;
DATABASE your_database;
BEGIN LOADING your_table;
DEFINE
column1 (VARCHAR(100)),
column2 (INTEGER),
column3 (DATE)
FILE=your_file.csv;
INSERT INTO your_table VALUES
(:column1, :column2, :column3);
END LOADING;
.LOGOFF;
```

Replace placeholders with actual values corresponding to your data and environment.

Once the data is loaded, write and execute SQL queries in Teradata SQL Assistant to verify that the data has been imported correctly. Check for any discrepancies or errors by comparing sample data from the Teradata table with the original data in the CSV file.

Document the entire process, including any SQL scripts used and any issues encountered during the data transfer. This documentation will be helpful for future data migrations and for training others. Ensure that you save the scripts and documentation in a secure location for future reference.