Birds and the Bees

So my daughter is turning 11 this month and starting middle school. She got her first period at 9 and of course she got the whole period talk but I didn't give her that specific talk. I want to give it to her before she goes starts school but I don't know how I should do it or what to specifically say for a girl her age. I was gonna tell her like basic stuff but don't what is appropriate for her age. Any suggestions??