Here, you need to specify Import Behavior, the options required for the proper file validation and select the exact methods your rates were created for in the Shipping Table Rate Methods section:
On the next step, please attach your file with the created rates. You may find the file template for the reference in the Import Settings section, as shown above. Once done, you need to check the details to make sure your import file & settings are correct:
Finally, if no errors are found, you may compete the import process by pressing the Import button: