How do you french kiss?
There is no "correct" way to french kiss. French kissing involves kissing with an open mouth. It often also involves using your tongue to touch the other person's lips and tongue.
There are many different ways to kiss someone, and it can be good to kiss in different ways. E.g., sometimes to use soft kisses on the lips without using your tongue, to gently lick or suck on the other person's lips and tongue, to softly kiss their face or neck or ears, etc. Some people prefer to kiss like this before they want your tongue right in their mouth.