I still cannot figure out how does it work, how can I mark the answer to be my best answer? I still cannot figure out how it works, and how to mark an answer to be my best answer. I still cannot figure out how it works, and how to mark the answer that is to be my best answer

I cannot figure/work it out. I don't know to select/choose the best answer.

Under each answer, there should be something like "best answer" that you can click.