The ring tones are formatted for iphone. Preview them by clicking the play button
The first ringtone is beautiful and slow - from a Guarania called Cancion del Jangadero
Second ringtone is from Tango A Trois Temps, starts with a pretty harmony in 3 3 2
The third ringtone is upbeat - from the Chacarera simple, La Olvidada - starts with Bass solo
The last ringtone is upbeat - from the Gato De La Prima A La Bordona - with Guillermo on Bombo!
To install the ringtones, download the files, open iTunes, drag and drop the .m4r files to iTunes, connect your iphone, click on the device in iTunes, make sure Sync Tones is selected in the Tones tab, and click Sync. ET Voila, the ringtones are on your phone and can be selected in the settings->sound menu of your phone.