How to finger yourself correctly?

I'm 16 years old and still a virgin.. nothing has really been inside me yet besides that one time I tried to use a tampon (that's a horror story for another time 😬!!). But anyways, I masterbate from time to time but only by clit-stimulation and that's been doing the trick but now I feel I want more.. without having to have sex. I want the feeling of something actually going inside me and it feeling good! I've tried to finger myself and I've started out by just slowly inserting my finger in my vagina as far as I can go. It felt really weird and like I would hurt myself if I moved it in any way besides forward and back. So I tried that and it didn't feel very good 😬. How do I finger myself correctly and in a way that feels good and isn't painful. How do I do it right ?