right click control

I would like to do a control within
the explorer (whilst browsing directories and files)

upon a right click one's already have
"open","cut", "paste", etc ...,"porperties"
for people who have zipp
you can also see "add to zip"

I would like to add something (dependent on the extension for exemple)

It seems to be a COM to write to be the control
but I've never done it before ...
and need a starting point ...

A simple exemple that would do the same thing as
"open with wordpad" would simply explain how to proceed !