You are correct, it does not work out of the box.
If you’re using Inform 6M62 (the latest), the version of Quixe it ships with is ready to display graphics, but you still, at this point in time, have to go through an additional (annoying but not-super-annoying) step of running a special Python script on your game to get the graphics files reformatted so they’ll work in the online release.
So you don’t need Simple Graphical Window or anything like that – what you were doing originally in your code is fine. The normal display an image function mentioned in the manual is fine. You don’t need to ‘do’ anything with Quixe other than have the right version, which you already do if you are running 6M62.
What you now need to do is create a release of your game with an interpreter, then run the the Python script on it… Instructions for doing this are kind of all over this thread I’m about to link to, but I’m going to link directly to the post from Angstsmurf that sums up in one message how to do it:
There are more message there from people having trouble, and more trying to explain how to do it 
I hope this can get you over the line.
-Wade