First find lowest common denominator (LCD) for all the fractions you are adding. That number is 6. Then multiply the numerator (top number) by whatever number you multiplied the denominator with to get the LCD. Then you can add the fractions once all the denominators are the same. At the end, reduce the fraction if necessary if the numerator and denominator are both divisible by a common number.
Answer to your question:
1/3 + 1/6
2/6 + 1/6 = 3/6
Reduce 3/6 to simplest terms
3/6 = 1/2 (Because both the numerator and denominator are divisible by the number 3).
Hope this helps a little. Thanks.