When washing your vagina are you suppose to use soap, unscented soap or like just water? Also is it possible to break your hymen by inserting a tampon in your vagina

It's best to use just water. The vagina is a "self-cleaning oven" so to speak.

Yes, it is possible to break your hymen when using tampons.

Water is definitely best when you use soap of any kind you take away good bacteria and when you take away that bacteria you are more likely to get yeast infection and breaking your hymen on a tampon is rare because the hymen is stretchy to a point plus they have junior tampons which are a little bigger than your pinky but you will know what your body can handle I started (at nine) with junior tampons but moved up because my flow was greater than the size of the tampon (and I am a small person) so if I were you I wouldn't worry about that