Inventor tutorial, and a simple question

I could use a tutorial for using Autodesk Inventor. I won't be doing
anything very complex, I could use a tutorial that exhaustively
covers the basics (maybe ideally using different words to repeat the
ideas more than once). Multimedia is useful here.
Now...
I am not an engineer, so I'm learning lots of terminology.
I am messing around with the program. I have two parts, a flat bar
with a hole in it, and a tube. The tube is slightly smaller diameter
than the hole in the flat bar. When the parts are placed in an
assembly, the tube can be magically dragged around through the flat
bar.
How do I stick the tube through the flat bar so that it is centered
in the hole? That's probably best. Or just make sure that the tube
is not sticking through the solid flat bar instead of the hole in
the flat bar?
Mainly out of curiosity. Is there some way to make the flat bar and
tube interact realistically? In other words, when one or the other
is being dragged around, it would not move through the solid other
part. I am not suggesting that is a good idea.
Thanks.