Masturbation have any relation to petting ?

Yes: Petting is touching someone else in ways that you can touch yourself, through clothing or not, to climax or not. It might be time for you to talk with a grownup you can trust and who isn't nuts -- perhaps a parent, it depends -- or an older same-sex friend. Especially before you think about marrying, you need to be well-informed sexually. Good luck, be safe, and enjoy yourself.