Open the labia minora and you can see the vaginal opening. The hymen of most girls is located at the vaginal opening. Looks like a piece of pink meat stuck in the vagina. Open it and you will see a small hole. This is the most common annular hymen.
Every woman's hymen is different in shape, position and thickness. So I'm not sure that's what you saw.
Don't put your hand in. The hymen is very fragile. I'm afraid I'll accidentally break it.
You can also find related pictures on the Internet. It is always good to know more about this knowledge.