First you need to get the same denominator on both fractions. You can do this buy multiplying the fraction by the other fractions denominator:
1/2 + 1/3
1/2 x 3 = 3/6
1/3 x 2 = 2/6
So the new expression with the same denominators is:
3/6 + 2/6
Then just add the numerators:
5/6