What you are trying to achieve is a piece of cake" with Hype...
Firstly set the scene size you want (size of the book?)
Add the image of the book to your scene as the background layer (must be at the bottom of your object list)
Use any flag image you like but cut the flag out from the background, delete the background and save it as PNG24 file (transparent background).
Import it to your media browser and drag it onto your scene (book)
Add a "square object" to your scene and resize it to the desired size and add the content to it (text, images).
Group the object now together with all the content.
Now add a new timeline and press the record button. Make the object group either 0% transparent or move it off the scene (invisible for now).
Now move the play head to the right for 1 or two seconds and make the object group visible again (100% Transparency or drag the object group back on the scene to the place you would like it to be.
Now select the flag and go the actions inspector (the hand).
Select "on mouse click / play timeline" and then choose the name of the timeline you have recorded for the object to become visible upon click.
If I would have been at home, I would have made a quick sample for you but for the next few hours I am away. Anyway, I hope this simple wotkflow will give some guidance...