These are the audio files for My Heart Will Go On. Download the file for your part, plus the file that is just called My Heart Will Go On, which has all parts.
An MP3 player should recognise the files as being part of an album called MCC July 2013.
In terms of instruments used, the file with all parts has all voice parts using a voice synth, there is no piano part for this piece as it is a cappella. In the individual parts, all the other parts are quiet as voices, and your part is played as a piano.