I want that when a player does a certain task a little GIF (a box with little picture and text that moves up, waits a bit and then goes down out of the Players view) appears. I think you have to make that with the HTML Editor. Correct me if I'm wrong. My Question is how you can accomplish that and how you SAVE the changes you made.

textadventure or gamebook?
What do you want to do with the html editor and what changes do you want to save?

Textadventure. When I try to change anything with the Html Tool it nevers saves!
For example add a picture in the background of the UI. And I know that there is a Option to add an background Image.