wat variable does your search page use to search?
also what method is your form using? if you are using POST you must change it to GET so that you can interfere with the search string in the URL...
If your search box is like this:
form............
<input type="text" value="put in something to search" name="search" />
everything else....................
Then, if the form's method is GET, you should just be able to go "search.php?search=something"
if the name attribute of your search box is different, just change "?search=" to "?{the name of the search box}="
Hope this helps!