When somebody ask you "How are you" what should be the answar if one wants to say i am fine and how are you?.

Question

Answer

"I am fine, how are you?"
"I am fine, how about you?"
"I'm fine.  You?"

There are many ways to say it

Answer

You can say just that: "I'm fine, how are you?"
Steve's answer is good. There are many ways to say it.

By the way, the word is spelled "answer." Good that you got the "w," though, that's where many people make a mistake.