In this step we will change the user who approves the holiday request. First double click on the holiday request workflow in the hierarchy, this will bring up the workflow editing view.

Then double click on the activity that represents the Yes/No question within the workflow. The "Edit properties" dialog is shown.

At the bottom of this dialog is the "Responsible" field. This field represents the user who is responible for this activity.
Right click on this field and select "Relationship", and the "Select responsible" dialog is displayed.

Select "Relationship type" to be "Line management" as we are interested in selecting the line manager of the requestor.
Select "Relationship direction" to be "B to A". This specifies that the requestor represents person B in the relationship and we want user A. If we specified "A to B" we would get the reports of the requestor rather than the manager.
In "User" enter "Creator", as we want to get the manager of the person who created this workflow (ie requested the holiday).
Finally in the default user, select "DB/Ann" as she is the CEO in our example so approves all holiday for anyone who does not have a manager specified.

See responsible script for more examples of how to use the "Responsible" field.