Need Help for Batch script to open a random folder in an already specified directory and open a random file in it

as mentioned in the title i need help programming a script, preferrably in batch, that will open a random file (in my case only pictures but with different headers) in a random folder of a specified directory. In addition to that it should work in a loop, meaning that the last opened picture should be closed soon after in order to create a sort of "dia-show". I am pretty new to programming so please explain me what you would do.

Thanks in advance