Well, you would need to set the location to a URL that points to a page that does the search. You need some server side page to do the actual search (like PHP, ASP, etc.). Do you have that in place?
To do the redirection it would be something like this:
location = 'http://www.example.com/yourSearchPage.php?r=' + regions.value + '&c=' + categories.value
In that example, this assumes yourSearchPage.php is expecting an "r" and a "c" parameter (and perhaps it also checks for a "p" parameter for provinces).