The most common prepositions to indicate time – on, at, in – are also the most common prepositions to indicate position.
A. "On" is used when referring to something with a surface:
ex : The sculpture hangs on the wall. / The images are on the page.
B. "In" is used when referring to something that is inside or within confined boundaries. ex : The wine is in the jar in the fridge./ The girls play in the garden.
C. "At" is used when referring to something at a specific point:
ex : The boys are at the entrance at the shop./ We will meet at the airport.