How do I update the information on my "app"?

I have at last finalized the new version of the Trados Studio manual, and now I need to update the presentation on the AppStore site. But I am totally at a loss as to where even to begin, since this is not a piece of software, and all the information I can find relate to software. 

But in fact, even if my "app" were software, I might very well be in the situation where all I wanted to do was to change parts of the presentation. And I cannot find any place to do that. (On previous occasions, I usually managed to find the right starting place and go on from there. Not so anymore.)

emoji