Hiho. I'm trying to jump ship from XSI to Houdini but having some troubles.

I am following the “CHOPs Deforming Geometry: Part 1” tutorial on the old school blog. I placed a grid node, followed by a null node. I want to put a “channel” node after that but can't get it. I see a lot of nodes relating to rigs but none called “channel”.

Did I press a strange button or something? Where did the channel node go?

:roll:

You are still at object level, rather than sop level.
Houdini makes a very clear distinction between objects at world space level, where you are at the moment, and the coordinate space for each object.
So, both nodes that you have are objects and you can go inside each one to their respective geometry coordinate spaces.
Select the Grid object and hit “enter”, which will send you to the grids geometry coordinate space, Sop space (Surface Operations) in Houdini speak.
This is the space where geometry is created and modified. You can also think of this space as where geometry is deformed.
In sop space hit the “tab” key and you'll get a menu from which you can find the Channel Sop. Once the menu is open, start typing “channel” and the menu will do a search for the appropriate entries.

Oh ok. Thanks for the explanation. I think it would have been very frustrating figuring that out by myself…

I still can't see where I went wrong though (following the blog's video).

Anyway. Solved! Thanks!

I had to look at the beginning of the video again to refresh my memory.
That was done using version 8 of houdini. The interface was quite different, as you could see, and that we didn't have the Shelf tools then.
In 8 you would immediately go to Sop space to start working, so it would be assumed that the viewer would know this.
Jeff's blogs are an amazing body of work drawn from a very deep level of experience. Generally they are of a more advanced nature and it is assumed you know some of the basics of houdini, including recognizing the difference in the versions.
That's not meant to deter you, as you've done just ask questions to fill in the blank spots. We all welcome the interaction.

Soothsayer-
Check out the free Foundations course on 3dbuzz.com. It walks you through the entire workflow and is based on the 9.0 UI.
That should get you up and running.