web page title change

I am doing some changes to our website and have just added a checkbox list which works great but I need the title of the page to change when I select more than one checkbox. Currently if nothing is selected it says “Summary for ….” Then when you select a check box it says “Summary for ….(name of checkbox)” When more than one checkbox is selected I need it to say “Summary for ….(multi)” I have found this code in the aspx.cs:

this.Title = "Summary for " + Container.Name;

       if (RegionId != 0)
       {
           try
           {
               this.Title += string.Format(" ({0})", NodeBasic.GetNodeBasic(RegionId).Name);
           }
           catch
           {

           }

       }

But I am not sure what I need to change and if I am looking in the right place? Can anyone offer any advice on it please?