Creating plugins

Creating plugins

I'm relatively new to jQuery, and love it. The only thing I'm having a problem with is transforming simple functions into plugins. I've got some code that will do an inline search and show only the LI's that match what was put into the #search_box.

Could someone please show me how to transform this into a working plug-in?

   // Extend to add case-insensitive :contains selector
   jQuery.extend(jQuery.expr[':'], {
         "contains-ic": "jQuery.fn.text.apply([a]).toLowerCase().indexOf(m[3].toLowerCase())>=0"
   });
   
   // Process search input to filter out relevant results
   $('#search_box').keyup(function() {
      $("li").hide();
      $("li:contains-ic('"+ $(this).val() + "')").show();
   });