To add fractions with the same denominator, add the numerators and keep the same denominator. For example, to add 2/4 + 1/4, add the numerators 2 + 1 to get 3/4. Fractions can look different but be equivalent, like 2/4 = 1/2. The document provides an example of adding 2/4 + 1/4 = 3/4 and gives an exercise problem of adding 8/15 + 8/30 + 2/15.