Custom Search Form

Having an issue with a custom search form I’m trying to do – I’ve got the form, but I’m not sure where to go with it next. I’ve searched for about 6 hours today and can’t seem to make sense of any of the forums or tutorials I’ve been over. Any help would be greatly appreciated.

Here is the form code:

<form method="get" class="ui-buttonset" id="searchform" action="">
<div id="radio" class="ui-buttonset">

<input type="radio" id="radio6" name="cat" value="8"/><label for="radio6">Contested</label>
<input type="radio" id="radio7" name="cat" value="2"/><label for="radio7">Uncontested</label>

<input type="submit" id="searchsubmit" value="Show Me My Articles" />
</div>
</form>

When I submit the form, I get the status of the two different radio buttons I’ve checked – “https://www.domain.com/texas/?cat1=7&cat2=9” but I’m lost as to how to make it pull results from the two categories. How do I process the radio buttons into categories…I assume the output would need to be something along the lines of: “https://www.domain.com/?s=&cat=7,9” but how do I make the form parse the radio boxes in that format?