That's actually quite simple if you can understand what to do.
If you want to make it 2 parts (collar and cape separate) than what you do is think how long you want the cape first, then cut it somewhat like this with the scoop being how big you want it around your neck, as well as the collar in the same way as pictured, and make sure the scoop and the bottom of the collar are the same length so it looks more uniform
http://s88.photobucket.com/user/RazorXCore_2006/media/kamina_zpsf1ef4356.jpg.htmlCut out 2 of the collar shape, then use stiff interfacing (whatever you feel is best, but get the fabric kind, not the walmart plastic crap). then iron it on, if you got the iron on kind, to one piece, then sew on the other side. Make sure the fabric is about 1cm or so bigger around the edges then the interfacing so the interfacing doesn't show. Then sew it together, where the outsides are touching (with the collar laying flat agains the cape as you can. I can't draw this, no idea how lol I think you get it though..There should be a seem that you can see on the inside..Isk how to explain it..
To do the cut up look on the bottom, what I did for my KH1 Cloud, I drew out with a black sharpie what design I wanted to start with, then cut it out kinda sloppy, then used a lighter to burn it.. BE CAREFULL doing this..