Simple steps

I have read the documentation, and watched the videos, but I am still not sure about 1 step.

I can create presets. No problem.

But how do I get the node to display the specific preset? I'm talking about the 2 places specified by the theme: "user pictures in posts" and "user pictures in comments".

I think I am supposed to edit the node.tpl.php, in the line that prints user pictures.

Please tell me the specific line I should edit, and please give an example.

I do appreciate this module. It is a wonderful tool.