Help with my girlfriend?!?

hey (im on my girlfriends acount fyi) so im 16 i think my gf and i are ready to take it to the next level and i want to finger her but i have never done this before. i know im a little old for it but i have wanted to wait until she is ready for it. i was just wondering what is the best position to do this? i dont think i will take off her shorts or anything the first time so how should we be sittin/laying or whatever. pretty much like on a bed, couch, side by side etc. thanks