Simple wav player with pwm & SD Card

I was confused with how play wav with SD Card data. I don't understand about all of meaning program. please help me...
I'm still newbie =( =( =( =( =( =( =( =(

What don't you understand? your post is very vague.

sciguy:
What don't you understand? your post is very vague.

I don't understand about dac conversion using PWM and read data with SD card