How to add additional url parameters?
If you are using l(), you would do something like this to create news?pid=3.

l('Link Text', 'news', array('query' =&gt; array('pid' =&gt; '3')));


If you have other query parameters, you can add them in like this:

l('Link Text', 'news', array('query' =&gt; array('pid' =&gt; '3', 'foo' =&gt; 'bar')));


and that would create news?pid=3&amp;foo=bar.

More information on l() here and url() here.