Which UML diagrams should I use for this?

Question

I have some classes (4) that are interacting and I would like to show how, basically what functions calls what and maybe the parameters.

I'd also like to show the flow of some operations, but for that I think activity diagrams would do, or maybe sequence diagrams.

Either way, I'm not sure what to use for the first case.

Answer 1

Sounds like a job for Interaction Diagram man!