Well, I believe your character has to be an adult, for one thing. Also, you'd need to be on at least the second generation (assuming you got all the TamaTomo symbols for your first generation) for this to work, naturally. Under the meal icon, you would choose the second option on the first screen, and then the second option on the second screen that comes up. This will take you to one of your ancestors' (any ancestor for whom you previously earned all 4 TamaTomo signs) house, where they will present you with a meal. Similarly, if you select the food icon, then the third option on that first screen, and then the third option on the second screen that appears, you will visit an ancestors' house, where they will present you with a snack. I recommend checking out binary's Menu and Stats topic if you're still unclear about some of the features. Hope this helps!