There is another button(picture) just below the top-right cornor (the one below close ejs window button)

Click that button and you will find another popup window.
The second tab is options and files.
You should add extral user files (click the check mark)

If you do not know how to do it. You can try to post your simulation as part of forum message:

You will find a checkbox labeled "Upload new EJS jar file" when you post message or reply to this message.

Please click that check box, and you can upload the jar file, and the EJS simulation will be added at the end of the message. ( or use can add [b][[/b]ejsapplet[b]][/b] and it will be replaced with simulation, too)

I need to have your jar file to test it out.
Or you can attach xml file and image file so that I can download them to test it.

It is 1:15 am now. I need to go to bed. I will try to answer your question when I wake up in the morning.