You have at least 2 ways to do it:

- Querystring
- IMC

in both approaches you will probably have a Lister module and a Viewer module, Lister is the treeview, and Viewer a view module which uses LoadControl functionality to load the specific user control in the module.

If you go via Querystring, it will be a little bit simpler in the begining, and your modules don't need to be on the same page.

If you go via IMC, at start a little bit more complicated, your modules must be on the same page.

For both things, check out the Module developers guide. If you go via Querystring... look up NavigateUrl function, if you go via IMC, lookup the Inter module communication functionality. They should be both described in that document.