First period

How should I tell my mother I am having my periods? Why shoud I tell her?

Remember that your mother went through the same thing you're going through. I'm sure she will be thrilled to find out that you are entering your 'womanhood'. As corny as that sounds, it's a big step. Your mother will be able to help with questions that you don't have answers for and give you techniques she's learned on the way when dealing with cramps or which tampon/pad to use. It wouldn't hurt to tell her, she can only help you.

well, I know periods plain and simply suck. but all girls have to go through it and is better to have an experienced person help you through it.