Decision Actions are created to make an action dependent on a previous successfully executed step.
In order to create a decision action, the dependent step must be marked as an optional action AND must execute successfully. See Making Steps Optional or Suppressed in a Test Case.
To Create a Decision Action
1. From the slider view, go to the step that should only execute if the previous step was successful.
2. Click on Action Log. 
3. Under the Standard Attributes tab, scroll down to Decision Action field.
4. Select the Decision Action that allows the decision from the dropdown menu. Note: Only the steps marked as Optional Actions (above) will be available for selection. 
5. Then determine the Decision Result Use as True/False. Example: Select True to create a Decision Action where "Step 3.1 will only execute, if the optional step (2.1) executes successfully."
6. Click Save.
7. The Decision Action is now identified, as shown below: 