De1-soc uart spi i2c

HII I HAVE THE DE1-SOC BOARD , AND I LOGED IN TO THE LINUX CONSOLE ON THE BOARD
on the board i can reach spi i2c tty devices under /sys/class

and my question is lets say i want to write a c program the send data using i2c

under i2c-dev there is i2c-0 and i i2c-1 , how do i know which pin is connected to i2c-0 and which connected to i2c-1 , are the pins accessible by a header on the board i be very glad for hel thanks