By default, you can have up to 3 different shipping levels.

You can easily change the wording ("Standard", etc.) by editing the text in the "English.php" file located in the "languages" folder of the Market Theme files. You can also edit this file through the built-in theme editor option under the "Appearance" tab.

If you need more shipping options, you'll have to modify the code a little.

This post doesn't speak exactly to the shipping dropdown boxes, but talks about the other dropdown attribute boxes. The logic between the two is very simliar though.
http://www.markettheme.com/for…..-attribute