Help with sorting columns using parameter

I have a report that has three fields (columns). I want to prompt the user at run time about whether they want to sort by the job name or job number. I know how to create the parameter but I am not sure how to do a dynamic sort.

I assume that I will have to create two groups one for each column and the suppress or show the details of either group depending on the parameter. Am I on the right track? Any links to some sample code?

This is a mock up of what I am trying to do

Code:

---

If {?SortBy} = "J" Then
    'Sort by Job Number'
Else

    If {?SortBy} = "N" Then
        'Sort by Job Name'

---