Example of adding an Item to a Category

Hi-

I'm stuck, please forgive me if this is a stupid question.

Is there an example somewhere of programmatically adding a catalogItem to
a 
category? I've found the catalogitemsdatatable.addCatalogItem method, but
I'm 
still confused as to how to make it happen.

In my case, I have a catalog called myCatalog, and a category 2 levels in 
called "myCategory" which is a child of "myParentCategory". I'd like to
add 
myItem to myCategory

Thanks in Advance,
Rob