The comparative & superlative of adverbs

comparative form:
1) + more/ less + adv
e.g. more slowly; less happily, etc.
2) change the spelling
e.g. well --> better

e.g. i walk slowly. --> you walk more/ less slowly.
e.g. i can speak well. --> you can speak better.

superlative form:
1) + the + most/ least + adv
e.g. the most carefully; the least happily
2) change the spelling
e.g. well --> the best

e.g. i can write carefully --> you can write the most/ least carefully.
e.g. i can sing well. --> you can sing (the) best.