how to make difference between the "s" and the "z" pronounciation?
can u give me some audio links. gracias

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S = es letra labial: la lengua no toca los dientes

Z= es letra labio dental: la lengua toca dientes inferiores por la parte de adentro

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mylanguages.org/spanish_alphabet.php

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la pronunciación de cada letra hace posible enteder una palabra y escribirla adecuadamente, La S y la Z tiene una pronunciación diferente y la C en los casos de Ce y Ci es otra y depende de la posición de la lengua asi también es el caso de la X la cual en México tiene los siguientes. 

Escribe Pronuncia 
México Mejico 
Xochimilco shochimilco 

toma en cuenta que cada pais Latinoamericano en que se habla español tiene sus propios coloquios y su velocidad al hablar le da a las palabras un sonido diferente de una nación a otra a una misma palabra y en varios paises hispanoparlantes el acento y la velocidad de dicción varia entre sus estados, departamentos y municipios inclusive.

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En los países latinos no hay diferencia entre "s" y "z" en la pronunciación, salvo en España donde la "z" se pronuncia como "th" en Inglés.

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I don't have audio links for you, unfortunately, (well I could upload some but am feeling lazy) but if your English pronunciation is acceptable, I can tell you how to make these two sounds.

If you can pronounce the English "s" in "six", you can use this sound as the Spanish s.

If you can pronounce the English "th" in "think", you can use this sound for the Spanish z, (and the c in "ce/ci")

Outside of Spain, and even in parts of Spain, it's common to not use the z sound at all, and instead use the s sound for s/z/c in ce/ci.  I pronounce z/(and c in ce/ci) as s because where I live nobody uses the z sound (the USA.)

Interesting side note: I once talked to a woman from Spain, from a place called Almería, I think, and she used z instead of s all the time.  For example, she pronounced "España" as if it were "Ezpaña."  Now that was interesting.

To be honest, if you're serious about learning Spanish, you should already have quite the collection of Spanish audio to listen to and shouldn't have trouble finding these sounds in your own collection of Spanish audio.  If you can, get some audio books or some movies or something in Spanish to listen to frequently.  I believe that it's never too soon to start getting your ears accustomed to the sounds of the language you're trying to learn.