My website (www.polidias.com) proposes ringtones to users of different
countries and languages. How can I ensure that the correct pages with
the correct language are shown in the correct country's search engine?
(e.g. spanish keywords tonos polifonicos / melodias to Spain,
Argentina, Chile etc. users; french (sonneries / mélodies) German
(Klingeltöne, Logos) France / Switzerland or Germany respectively?

Greetings!

You will need to have specific webpages written for each language, and
use the web server (IIS) to switch based on the language accepted be
the viewer.

Or, you can write the pages in ASP code, and have the code detect what
languages are accepted by the browser, and use the appropriate one.

A full solution is beyond the scope of this question / fee.  However,
some preliminary reading is listed below.

W3C Internationalization (I18N) Activity
http://www.w3.org/International/

Internationalize Your ASP.NET Applications, DevX.com
http://www.devx.com/dotnet/article/6997

Internationalization References
http://www.i18ngurus.com/


Search Strategies:

internationalization
://www.google.com/search?q=internationalization&sourceid=mozilla-search&start=0&start=0&ie=utf-8&oe=utf-8

internationalize IIS
://www.google.com/search?q=internationalize+IIS&sourceid=mozilla-search&start=0&start=0&ie=utf-8&oe=utf-8