To mark someone Brainliest you must click the crown.
Explanation:
Let me explain, in order to give a Brainliest, conditions must be met, meaning that 2 answers must be provided. But if you want to know how then first go to the answer you want to give Brainliest and scroll down to the heart and stars, to the right you will see a crown, click it and, Boom you reward the answer a Brainliest.