Begin by exporting your data from Smartsheets. Navigate to your Smartsheet, click on "File," and select "Export." Choose the format that best suits your needs, such as CSV or Excel. This file will serve as your raw data source for uploading to Firebolt.

Open the exported file and format it according to the schema requirements of your Firebolt database. Ensure that column headers are accurately named and data types are consistent to avoid any issues during the import process. Save the file once it's properly formatted.

If you haven't already, sign up for a Firebolt account at the Firebolt website. Once registered, log into your Firebolt console. Follow any setup instructions to get your environment ready for data import.

In your Firebolt console, navigate to the SQL editor. Use SQL commands to create a new table that matches the schema of your prepared data file. For example:
```sql
CREATE TABLE my_table (
column1 STRING,
column2 INT,
column3 DATE
);
```
Adjust the column types and names to match your specific data requirements.

Use Firebolt's native file upload feature to transfer your prepared file into Firebolt. This can typically be done by uploading the file directly through the Firebolt console or by placing it in an accessible storage location (like an S3 bucket) that Firebolt can access.

Once the file is accessible by Firebolt, execute a command to load the data into your Firebolt table. For example, if using a CSV file:
```sql
COPY INTO my_table
FROM 's3://your-bucket-name/your-file.csv'
FILE_FORMAT = (TYPE = 'CSV');
```
Make sure to replace the placeholders with your actual bucket name and file path. Adjust any settings needed for your file format.

After loading the data, run queries to verify that the data has been imported correctly. Check for discrepancies or errors by comparing a sample of the data in Firebolt against the original Smartsheet file. Use Firebolt's querying capabilities to ensure data accuracy and completeness.

By following these steps, you should be able to successfully move data from Smartsheets to Firebolt without the use of third-party connectors or integrations.