Hi ! I'm new on this forum and on Hammer. I have some questions on Hammer.
1/ How to create new models, materials, and objects like this one : http://www.geekanerdblog.com/2007/10/po ... od-on.html or this one box catcher : http://www.youtube.com/watch?v=MhrP22RjP3Y
2/ How to integrate'em on our maps.
Thanks.

Generally, I would point you to the "New To Hammer?" thread, which you should really check out, but I doubt that would give you the answers you want.

The sort of witty, tautological answer to your question is that you 1) make the model in a modelling program and 2) integrate it in into your map by including it.

For the first, there are many different options for what to model in. I think 3D Studio Max has a following around here. As for the second, as far as I know, the only way to go is PakRat.

A free 3D-modeling program is Blender 3D, though it's kinda tough to learn (as are all such programs). I've been struggling with it for some time and I still can only create a bunch of flat boxes...

You can get more information and download the program here:
http://www.blender.org

For tutorials, I'd suggest searching this site:
http://www.pixel2life.com

It takes a lot of time and effort to become a good 3D-modeler. You will need to spend huge ammounts of time in order to learn even the basics. But tutorials are always a huge help, and it will only be a matter of time before you can create anything you want.