Please, I need EASY and CLEAR steps on how to set and access an external disk connected to my airport extreme over the internet

Hi everybody (anyone speeking spanish by any chance?)

Anyways, I've already found some detailed steps of how to do it but they either are written for an older version of the Airport Utility (with different labels, and fairley less setting options), or the lack of explanation of how to set the modem first. In both cases, the info is not accurate or clear enough.

Can anyone give me a hand on these, it's becoming really anoying having bought the Airport due to this feature and having such a hard time trying to make it work.

Cheers everyone and I really hope someone could lead me on this.

Enrique