To find the common denominator, self-add the denominators until they reach a common number. I will self-add 6 and 8 for 5 times each until we reach a common number.
6: 6, 12, 18, 24, 30.
8: 8, 16, 24, 32, 40.
They have a common number, 24.
Your least common denominator is 24.
I hope this helps!