lesbian sex????

Ok so im bi but i have a girlfriend i want to lose my virginity to her but i dont know how to. She is also a virgin. Um i looked at pornhun and all the others but everything seemed extremely fake. So how do you have gay sex who sticks what in who. Also how do you know you will be the dominant one? Wouldnt she be though because im a girly girl. And she tends to dress on the tomboy side