You might guess that this is a very, very common question, which means there are plenty of explanations and exercises already online. Just do a search for "difference in on at". Feel free to ask if there's something specific that confuses you.

in, on at You use "at" when talking about time and/or place for example "The party starts at 9" (time) or Lisa is at home. (place). You use "in" when something is physically or figuratively inside something , or in regards to time when something is within a certain time frame. For example " Mary lives in Los Angeles (she is physically inside the city of Los Angeles) or " The games starts in 20 minutes" (the game is starting within that time). "At" is a little harder to explain- when first learning English it seems as if "in" and "at can be used interchangeably but with practice you will be able to recognize what sounds more natural.

There are not any general rules, unfortunately. You will just have to read more, absorb and remember. Let me give you some examples to illustrate the absence of general rules. on the road in the street on a bus in a car

In On At they are not the same. Experience with each will show you what the context for the use is. You can be "in trouble" or "in luck" or "in a house" or "in the hall" or "in the mud" or "in a confused state of mind". Your food can be "in the cooler". You can be "at the bank" or "at the airport" but you can also be IN the bank and IN the airport. You can also do something "at once" which means immediately. You can be both IN the grocery story as well as AT the grocery store. You can be IN the airport and also AT the airport. You can be IN the Library and also AT the library. Your books can be "on the table" and your food can be "on the table". Your name can be "on the schedule" and you can be "on the list". Your food can be "on ice". My best advice to you is to study all the books you can and all the websites for English study. Start making three lists. Copy all the sentences using each word as it appears in a sentence until you have a certain guide for their use.