How are theads, Tid and spawn related?

[Neven via Digitalmars-d-learn]

Ok, a newbie question ahead. I want to create new thread which 
calls given function with some parameters. Thus, I think spawn is 
the right function for me. However that functions returns Tid and 
not a Thread object.

So I want to know how can I make a Thread object out of it. What 
I would like to achieve is to wait for spawned thread to finish 
its execution, that is join with main thread.