In addition to
alanp9 guide, I'd like to add some precisions for getting this achievement, especially where to find dragons the quickest and easiest way.
- The dragon you will capture while you are going through the main story of Dragonborn DLC
does count toward the achievement.
- You will be able to find a dragon at the
Throat of the World,
- You can also fast travel to some places where there will always be a dragon neaby, when you look at your map, these places are represented by a
dragon head.
The video below shows you where to tame dragons, the quality is a bit poor however.