I finally understood how to attach files. So here goes my epub comic. I made it from the template on
http://www.jedisaber.com/eBooks/tutorial.asp
If anybody wants to try it, I will be glad to get comments. It works fine on my prs-300. But as it has one of the smaller screens on the market, I would be interested to hear how it goes on bigger screens.
I will also try using the templates from Jellby and ralphsnart in this thread to see if it looks better