cross correlation

Hello,
My name is maz and I am working on simple sound source localization. I
have to find the location of a sound source on a 2d plane. (I am not
considering z axis). I have 4 mics placed on a wooden platform, the
co-ordinates of which are m1(0,0), m2(0,6), m3(4,6), m4(4,0). del12 is the
difference between the distance from mic 1 to the source and from mic 2 to
the source. del12=(delay between the 1st mic and the 2nd x v sound i.e.
340m/s)/fs i.e. 44000. My question is how do I calculate the delay between
these two sound signals using cross-correlation in matlab. (I am not
considering sound for the start as i have taken the readings in a sound
free environment). I do not know since I am still learning. Can you please
explain with the help of the matlab code. Thank you.