As far as I'm aware there is no such shortcut designed into avast; think about it, that could introduce a weakness if such a shortcut could be made, then in theory it could be used for other shortcuts.
Not sure what you have in the way of screen capture applications (I use SnagIt for screen captures, but it also does videos), you could do a short video of the steps to do it, so that little tutorial video could sit on her desktop.
Or just a short series of screenshots as a guide.