Step 1 : Assume the percentage as grams and divide it with molar mass.
Step 2: By this way you have calculated the number of moles , further divide evey term with the smallest term which you have calculated in step 1.
Step 3 : Now you have the simple whole number ratio of elements just put these numbers as subscripts on the lower side of the symbols of elements and u will get the empirical formula.
66.67/12 =5.555 moles of C
7.41/1 =7.41 moles of H
25.92/14 =1.851 moles of N
5.555/1.851= 3.001 for C
7.41/1.851= 4.005 for H
1.851/1.851=1 for N
So the empirical formula will be C3H4N .