This site is dedicated to owners of a Samsung a900 cell phone. Its purpose is to help you place mp3s onto your phone to use as ringtones. By default, the a900 does not provide that option.
Despite the name—a900hack.com—this site is not a "hacking site." It does not help you modify your phone's firmware. It does, however, help you browse your phone's file system and place modified mp3s in key directories. For more information on how to do this, please see the "How-To" page in the navigation links above.
Once you understand how this process works, use the "Upload" page to convert your mp3s to the files required by your phone.