Apple Crumble

My English teacher gave me cooking apples from his garden. They were fresh and looked very tasty however I didn't know how to cook cooking apples.
My friend brought caster sugar, a scales in ounce and a pyrex dish for baking and helped me to make typical English sweets "Apple Crumble" in my place. It was very tasty! My friend told me it's easy to make but I didn't think so. Hum... I'm not sure whether I can taste this once again or not.