Searhc Function

I am wanting a search function added to my site, the will search fice of my sub domains and the show results listings where they are ie two sub domains are wine, cheese, so the results would show like (with x being the search result); Wine xxxxxx xxxxxx Cheese xxxxx xxxxxx xxxxx I want to be able to add more sub domains to the search look up as time goes on. This involves the creation of the results page.