Mayank forgot to tell that you are not obliged to rename the Decisions. For once it is OK if all decisions keep the same name 'Untitled'. However if you want to give a better label (as is the case for all use cases on my blog), be careful not to use a name that has been used elsewhere for another object or even for an advanced action, a variable.
You cannot have less than three decisions, but you don't have to use all of theme. And since CP7.0.1 it is possible to duplicate a total decision (third icon under the Decisions),and to move the decisions. Sequence is as always very important for conditional actions, most files I debugged did not respect that logic. And all decisions will be checked, contrary to normal programming languages.