In this case, it would help if we knew what age-group we are advising.
We don't judge, and this is nothing to be ashamed of since it's the most natural thing in the world for a couple. Just think of how far both of you would be willing to go, and be natural. Be aware of dangers and consequences if you go further than recommended for your age-group and are not careful. So, bottom line, talk to each other and get educated and do what comes naturally and safely.
Don't let your peers talk you into doing something you are not ready for just because they tend to brag a bit - since young people also like to play tricks on their peers just to see how far the others would go.
The more you communicate and get to know your 'gal' the more fun both of you will have, so for goodness sake talk with her, and keep up that warm arm around her unless she says to stop.
Good luck and have fun growing up!
Keep us posted.