coolant leaked out

You need to have a shop pressure test the cooling system to determine exactly which parts has failed and you can check cooling system diagnoses prices here https://repairpal.com/estimator/bmw/323i and locate a shop near you here https://repairpal.com/bmw-repair-in-sonoma-california Call a local shop and if your BMW is overheating you probably should have it towed to avoid damaging the engine

obvious spots at the radiator. Not so obvious: around the throttle control. There's two hoses there, a supply and return.