I'm not sure what you're looking for. You can add query string variables to the url manually in the wizard as well.
If you put this into the url:
that's where the menu item will link to including the query string variable.
Dynamic menus basically put a menu in the site for each item that's returned from the table (after filtering and sorting). Dynamic menus work differently in that you can either store the url in a database and directly output the database url into the menu or store the query string variable's value in the database and dynamically add that to each of the menu items that correspond to the database entries. You will still have to add the ?query_string_name= to get the variables added.