Elemented Bend

My book

I could see the headlights of one of my parents cars pull into my drive way. My light pink book light was on and shinning on to page 52 of the book I was reading, called ---
My door opened,
"Hey ava! Just wanted to make sure your ok, I heard that the police were driving around town and warning people about those 5 element things that were stollen. Oh well... well good night" it was my dad. Though I was to caught up in my book to really notice what he was saying and doing. But one thing did stay into my mind... the words, 5 elements... but the book only talked about there being 4 elements, water, fire, earth,and air. But why did he know what an element was... Oh well must be an adult thing I wasn't going to let a tiny thing like that ruins my night of sleep. I read on, up to around page 64 until I was so tired I was going to passout. I was about to put the book down, but then my finger slipped on a folded paper at the back of the book. It was even older than the book it's self. It read,
  
         Dear Clarra,
  Being one of the welders us hard enough, I need you to take the last element. It's a big duty, but the war against the fire nation Wil need am the help it can. Weild the chi-blockers elements even if it means I will loose mine.
        Love your sister
                   Martha

       I flipped over the paper and There was a date. 1609...
This note was a relec. Why was it in a basement. There's to many mysteries in this town. But one mystery I could solve, was the one I was thinking if the most. I was bought here for a reason...