Install dewplayer in a phpbb forum

Hi from Spain. I'm a newbie.
I want to add tje dewplayer in my phpbb3 forum
audioforo.com
But I just don't know why.
would you help me, please?
Where have i to add the code? in which file?
Thanks in advance

Hi and welcome,

Note for others : I'm the one who asked paco to sign in here and ask its question. English language welcome when french isn't possible.