Can anyone sugest a method or stages of a method to find out the iodine number of a fat or oil. Thank you very much!!

Have you tried to Google "Iodine Number?" A quick search found several references that might fit your need

no way, Google isn't too much help

In = (a-b)/c x 1.27/5

Where, a = blank titration
b = mean sample titration
c = mass of oil in sample