Talking to your daughter about periods may seem awkward, but it is essential. Your daughter needs to know what is going on with her body and to know that it's a perfectly normal and natural thing. Sometimes, schools will show students a video to help them understand what is going to happen. Even if their school does this, it is important that you talk to them about and make sure that they know it's OK to ask any questions.
When do I discuss it with them?
Periods can start anywhere between the ages of 8 and 20. You want to talk to them about it before their first periods starts. It's pretty easy to predict when it's going to happen; just look back on the family tree. Often times, girls will take after their mother when it comes to periods. So if the mom's period started young, there is a good possibility that the daughters is also going to start young. Just keep in mind that everybody is different, so you can't tell them exactly when it's going to happen.
I learned about periods when I was nine, which is about when all of my friends also learned about them. Our parents encouraged us to start keeping pads in bags so that if it were to happen, we would be prepared. It was a good thing to, because within a couple of months some of my friends started to have theirs.
How do I explain it to her?
Each child is different. Different personalities are going to learn and understand things differently. You need to make sure that they understand what is happening with their bodies. Make sure that they understand that this means that she is capable of becoming pregnant (though you might want to throw a "when you get older" in there) and that it is a perfectly normal thing that all women go through. Another good point to bring up is that it doesn't happen at the same time for every woman, so it's fine if hers is sooner or later than her friends.
How do I bring up pads/tampons?
Having examples on hand will help. Obviously, after you explain what is happening to their body, you need to explain how to take care of yourself while on your period. You should mention pads and tampons as you explain proper period hygiene.