Click Run on a desired procedure.
Use the OPERATION drop down menu to select the operation.
For running procedures, you can also type in this field and select the Create option to create a new Operation.
Once an Operation has been set, you can change the Operation by selecting a different Operation from the drop down menu, or you can remove the Operation by clicking the x in the filed.
If the run has ended, an Operation can only be added or edited. You are not able to remove or create an operation from an ended run.