How to make my containers pick up liquid

I'm making a mod that adds drinks to the game, and I'm trying to add the ability to fill mugs by right-clicking water, but there are no explanations of the functions features or how to do this on the forum, I've been looking for 3 days now I just need someone to tell me which functions specifically I need to use I can figure out what order I need to put them in, I just need to know which ones as there is no page explaining the function of each function on the program.