An adjective modifies a noun. An adjective tells more about how an object looks or feels.
An adverb modifies a verb and tells more about the action.
Good is an adjective. Use good to modify a noun.
This was a good dinner.
Sam is a good boy.
We watched a good movie.
In each of these sentences, good modifies a noun.
Well is an adverb. Use well to tell more about the action in a sentence.
Mary plays the violin well.
I hope you feel well soon.
We did well on our school project.
In each of these sentences, well tells more about how something happened.
Remember: use good to modify a noun. Use well to tell more about the action.