Mate, its really really easy.
Heres some advice though, try doing it somewere dark like a cinema or make sure its nighttime (since its winter this aint hard). Start off by kissing her on the cheek and then kiss her multiple times around that area (like you would kiss your mum when you were little - wrong but right), then move your way closer to her mouth and if shes up for kissing you, she should open her mouth a little, just stick your tongue in and brush it against hers! Then take it back and then stick it back in, keep doing this and thats pretty much it, make sure your lips are locked etc and that should be pretty much it...I think?
Actually reading back this all sounds a bit complicated and I probably didnt explain it right...
Oh well, just go for it mate, it comes naturally and its pretty damn easy.
EDIT: MAKE SURE YOUR EYES ARE CLOSED THROUGHOUT.