Good is used as an adjective (a describing word).
I ate a good dinner last night.
Our school has a good soccer team this year.
In each sentence, good modifies a noun: good dinner, good soccer team.
We also use good with intransitive verbs where the word after the verb describes the subject.
The dinner was good.
The wind feels good in my hair.
Good modifies the dinner. Good modifies the wind.
Good can also be a noun. The noun good means positive actions and behavior that are morally right.
This charity does much good for the community.
A person who helps another does good for them.
Well is an adverb. Use well to describe a verb when you want to say that the action is done adequately or up to expectations.
Sue does her homework well.
The band played the music well.
He taught the lesson well.
Well also refers to your state of body or mind – your state of health.
When someone asks, “How are you?”, you can answer, “I’m doing well.” or “I’m feeling well.“
I’m well means you are not sick.
I’m good means that you are fine just the way you are and don’t need anything.
I’m good can also mean you excel at something – as in I’m good at tennis – or that you are well-behaved and not naughty.
Finally, well can be added to adjectives with a hyphen, like this:
The good puppy is well-behaved.
That was a well-done essay.
The book is written by a well-known author.
Using good and well correctly takes some practice. Follow the rules on this page, and you will be fine. You might even become well-spoken and good at grammar.