"Either" and "neither" are used in almost the same way as "so" and "too," but they are used with negative verbs.

Examples:

I didn't get enough to eat, and you didn't either.

or

I didn't get enough to eat, and neither did you.

Pay attention to word order. "Either" goes at the end of the sentence after the negative helping verb, and "neither" goes after the conjunction, then the helping verb, and then the subject.

It's important to notice that words following "neither" are not negative. You shouldn't use double negatives in English.