Zoomer interface is simple. I tried to make it as easy as possible to be understandable without any help such as what you are reading now. So, I hope this help will not be necessary for you.
The main window is separated most time onto two parts:
In the Move-to-folders mode, the third part is appearing at the left side, which contains a list of directories to move files to. (Not available in Lite version)
In the Edit Collage and Print mode, the View area is replaced with the Editing pane, allowing to easy create collages, modify images, and save or print the resulting big image. (Restricted in Lite version).
The layout of the File list and the View area can be changed from vertical to horizontal: just double click the separator dividing it (or select a popup menu on the separator).
There is a Single view mode also, where File list totally is hidden and the View area is occupying the entire main window. To go to the Single View mode, just press <Enter> keyboard key or double click the view area or a file in the File list area. And do the same to return back to a normal mode again.
Each of two main areas described above has its own popup menu assigned, allowing control of context-sensitive options and commands. These menus are described in correspondent topics below. The main tool bar contains buttons calling most important commands for File list and currently viewing image. It is disappearing only in the Full screen mode, but all its operations still available in such mode via keyboard shortcuts.