Reach level 3 to learn Eviscerate, then find a training dummy in New Tinkertown and practice using Eviscerate 3 times.
As you learn more and become a better rogue, you'll start to learn new abilities.
One of the most potent ones is to chain together moves in a combination, exploiting your enemy's weakness and opening up the opportunity to use stronger maneuvers. Go, get some more experience and figure out how to do it. Once you can, come back here and try it out.