Bonjour Jane,
French prepositions can be a tricky thing to master, especially as they aren't always exactly the same in French and English. I do remember this topic very well when I was learning English: I always found it very 'drôle' to say 'I live ON a farm' as if the farm were an object you were located on, like a mug on a table. This grammar topic shows just how one language considers things differently from another. And by practising more and more, things will fall into place. I know how you feel though but don't give up! ;-)
J'habite à la ferme = I live on a farm
Qu'est-ce qui se passe dans la rue ? = What is happening in the street?
J'ai fait de l'équitation sur la plage = I did horse riding on the beach → verb of actions with ‘sur la plage’ (marcher = to walk, courir = to run…)
Je l'ai rencontré à la plage = I met him at the beach
Je vais à la plage = I am going to the beach → aller à + place
I hope this is helpful.
Bonne journée !