How do you kiss?
With your lips..
It comes naturally!
It depends on what you mean on how to kiss. If you mean you don't know how to kiss, just lean in and go for it. If you want to know how to give him/her a kiss, just do a little peck and if he/she likes it, give her another and another
There's a video by "gradualreport" explaining in detail what to do. It's called "How to kiss" I encourage you to check it out. It works miracles.