First off, when you get that frustrated the best thing to do is to slowly and carefully set the knitting needles down on the nearest flat surface and walk away. Do something else for a while and come back to it after you've succeeded at accomplishing another thing. Knitting is fun and when you're that annoyed with something it ceases to be anything close to fun.
Then when you come back try again. I honestly didn't learn to cast on here at KH. I used another site. The Lion Brand site is the one I found most useful for myself (http://learntoknit.lionbrand.com/
). I've watched someone do the method where they use their thumb instead of a right hand needle and for some reason I just can't do it. I also used some of the videos at Michael's website(http://michaels.com
I just cast on over and over for a while when I started knitting. It's good practice since you'll use it for a good long time. I call it a foundation skill. I'd just cast on for 50 or so stitches and then unravel it all and do it again. Your hands haven't memorized the motions yet! It's okay!