MDfly AU5121s controlled by NANO

I am trying to control the MDfly mp3 player AU5121s using a NANO. I am getting stuck at the serial communication using HEX codes. the spec sheet that MDfly provides gives a list of commands that can be used in the for of HEX codes (see http://www.mdfly.com/content/downloads/boards/audio/AU5121Sspec.pdf)

I have set up a serial connection using the softwareSerial.h library and successfully sent commands to play a specific file (mySerial.write(0x01);) but when I try to send command to control the volume or pause and resume I am unsuccessful. I think that I don't understand the HEX thing.

Has anyone used this Module that can give me some example code for these commands?

Using the serial port on a '328P:

Serial.write (0xEA); // play Serial.write (0xEC); // pause Serial.write (songArray[song]); Serial.write (0xEF); //stop Serial.write (0xE8); // volume up Serial.write (0xE9); // volume down

Have you used these commands yourself or are you just pulling them from the spec sheet. I have tried them and I get no discernible results.