These covers will fit the traditionally-sized YA book.* Take the PDFs to your local FedEx or Staples and get them printed on tabloid paper (11x17in). We suggest a matte cardstock (you could print on something glossy, but sometimes that causes light glares at certain angles and you want people to be able to read that Go Away message without incident). Choose a weight between 60-80lb for the paper. Anything lighter and the page will be too thin, anything heavier and folding it around your book will be difficult. You can have the store cut the printer-outs for you (it will cost a little more), or you can handle it on your own when you get home (there are crop marks in the files).
*There are of course exceptions.