The WB and UPN networks are not available nationally on DirecTV but if you live within one of the local cities that Directv does carry both networks (New York I think) then you would receive them within your local channel package.
This thread might answer some other questions about why WB and UPN are not on DirecTV. http://www.hometheaterforum.com/uub/...ML/002132.html
I am not sure with Direct, but with Dish (which i have), UPN and WB have to be purchased separately from their conventional programming. It is deemed the SuperChannel package. Another $4.95 a mo.