Displaying categories and loading an image gallery with curosponding images of that category dynamically in android?

Part of my app have a login option from which user will see 3-4 dynamic options and when they click on it, it intend to a gallery with images that corresponds to that particular option.. for example if the option is picnic, it takes them to picnic gallery..

But im clueless about displaying images from dynamic categories..plzz help me out..