So, you have a dataset with columns ABar, BBar and FooBar, you have three param objects which do not actually have a value -- they just have the sourcecolumns set, and the versions to tell how to transfer the updated value (whether to update, merge, etc -- docs should say that).
For return values, just return the value and setup the param as @RETURN_VALUE and a parameter direction as ReturnValue (check "Output" if that does not exist in 1.1)
I'm a bit confused on the comment about lack of documentation, there seem to be gobs of resources on the net for anything sqlcommand / dataadapter related. I searched for a couple of the above and found lots of hits. Just bounce around 'ole google. .net 2.0 and 1.1 are very similar in how they implement the command object, so you should be able to look at those examples too.