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.

When you constrain the tube to the hole in the flat bar, use an "axial" constraint (or perhaps a "co-axial" constraint). Creat a constraint by picking the axis of the hole, then the axis of the tube (you may have to "turn on" the axes to see them in making the selections). Then the tube will be centered in the hole, but can still be moved or translated to different depths in the hole. I believe Inventor comes with some tutorial files, buried somewhere on the DVD. Hope this helps.
Babygrand