Basic magnetism on square loop question?

[helpmeplz!]

A square loop carrying a current I creates its own magnetic field. Describe the forces on each side of the square loop due to its own field. What is the torque it experiences?

My question is this. I know we can use bio savart. But for bio savart, B=uoI/2piR, what R do I use? suppose i have a square loop, the adjacent sides do create B fields that the other experiences, but if they are two consecutive sides, their distance apart is 0? Please someone help me out!

 

[mfb]

You have to integrate over the lines, using the distance between the point where you want to calculate the field and the point where your integral "is".