Kissing comes naturally when you are in a romantic situation.
the secret is to provoke that situation.You first need to make the girl get used to you touching her first:
give your hand when crossing together a road, lay your hand on her shoulder when you say thank you, touch her hair and say that it's beautiful under the sun ...
then the kiss will become easy.
When you are alone speak low and make her close to your body and when you feel that she becomes receptive then give her a simple warm kiss on the lips.
don't use tongue, make sure you mouth don't smell bad or better take a shewing gum anyway.
a short kiss then squeeze her in your arms (it's a great feeling too).
if the kiss was nice for both of you try another longer one
good luck