Sewing curved pieces together takes practice. The absolute easiest DWR pattern I've ever seen is Rings That Bind by Cheryl Phillips.
http://phillipsfiberart.com She has the arc ease tool on her site but it looks like you'll have to shop around for the book or look at the demo she did for Simply Quilts. It's pretty straight forward if you have the tool & watch the video; I don't think you'll need the book.
http://www.hgtv.com/video/wedding-ri...deo/index.html
There are 4 different videos, I believe, and at one time there was a single page with directions.