How do you add dissimilar fractions?

If you mean adding fractions with different denominators then the first step is to find the lowest common denominator (LCD) which is the same as finding the lowest common multiple (LCM) as for example 1/2 + 2/3 of which the LCD or LCM is 6 and so it follows that 1/2 = 3/6 and 2/3 = 4/6 thus 3/6 + 4/6 = 7/6. or 1 and 1/6 as a mixed number.