How to kiss a girl if you're a girl?

Ok so I'm in middle school and i am a girl. I've recently discovered my biual side. I have like this one girl since the beggining of time and i'm now going out with her since a week ago. the thing is we havent kissed. everyone is asking if we have and I want to kiss her A LOT TRUST ME! but she is very very experienced in that area. and i am NOT. so im super nervous because i already have a serious self confidence, low self esteem, paranoia problem and ive totally flipped my sht about kissing her. she also wants to kiss me too but im TERRIFIED!!!!!!!! but i want to. so what should i do? she said she would get me over my fear but im mortified bout it. how do i kiss someone so experienced? will i totally mess up? is she gonna like start making out with me asap? how will i know what to do? what if she totally like uses tounge or trys and i flip my ****? what is ii have a heart attack???????? btw i have kissed someone before but i have never felt this way about anyone.....help help help