menu not showing on page with shortcode

First of all you should check if you insert shortcode with proper gallery ID. Namely which exist in gallery manager and you have uploaded images to this gallery.
If after such basic check you can’t see gallery in your post/page try to check your theme or some optimization plugins which could cut off shortcodes from the page/post.
For the top menu you should create few galleries and build gallery tree in categories manager. When you open settings of every gallery on the right side you can find block where you can manage all categories. When click on categories management buttons you’ll see popup with list of the categories. Just drag and drop items from the list to make some of them work as sub category. This way you can build categories tree.
When you create this structure try to open root gallery on the front end and after that you’ll see gallery with menu on top.