Understanding the Comma: How and When to Use It

Rewrite and insert commas where needed in the following sentences.

I need bread milk eggs and butter from the store.

My dog who loves to play fetch is sleeping in the yard.

After school I usually go to the library to study.

I need bread, milk, eggs, and butter from the store.

My dog, who loves to play fetch, is sleeping in the yard.

After school, I usually go to the library to study.