Relative Adverbs are so called because they are derived from the stems of relative pronouns. They not only modify verbs, adjectives or adverbs, but also join sentences. So they are sometimes called Conjunctive Adverbs. They are: How, when, where, whereas, while, why, ...

I cannot say how I found my way.

I’ll tell you when I am ready.

You will have to go where I tell you.

He was well educated, whereas his father could not read.

Ask him why he is so angry.