Question

How are most adjectives changed into adverbs?

Answer 1

An adjective is a word that descirbes something.
The turtle is slow.

An adverb is a word that describes an ACTION.
The turtle walks slowly.

Most adverbs are formed just by adding -ly to the adjective.

Answer 2

Mant times you just add "ly" to the word, like these examples: careful becomes carefully, quick becomes quickly.