Thanks for your reply!
The problem is that this County field is simple select. So it doesn't allow you to choose two or more. But the idea is good. So I set the field at the content type to checkbox and I set a generic search for this field at the search type. So now we can add two or more county for contents so job is almost done, but there is a new problem... :s Now when I want to create a new content, or edit an old one, there is a limit of 15 on the checkbox. Why? I tried with multiple select, but still the same 15 limit.
Greetings!