When you're feeling frustrated and can't figure things out, take heart:
I have been knitting for over 40 years, every kind of needle, every kind of yarn, every kind of pattern, every kind of technic, including teaching all of the above. I have been working on a sweater for the past 2 months. Any perusal of the many, many websites for corrections will tell you how many errors there are in knitting books. So no surprise that there were a couple of glaring mistakes in the directions in this pattern, which I cleverly fixed as I went along. Tonight, I was putting on the neckband, and realized, uh oh, those weren't errors, yes they were, no they weren't, yes they were, no they weren't, and finally came to the inargueable conclusion that oh yes indeed, the pattern was absolutely correct and this would have come out perfectly had I left well enough alone. Several choice words later, I began that time-honored ritual of picking out the shoulder seams and the casting off, and then pulling back far more yarn than I care to tell you.
So just be reassured when you, too, are in the midst of the deepest pond, with the biggest bull frogs imaginable, ripping your stitches (and heart) out, it ain't just you, baby. It happens to the very, very best of us.
Oh, and another reassurance-- even with all of my experience, my hand is also raised for not being able to figure out the provisional cast on video on this site-- I tried it out of curiosity after reading other posts, and I can kind of make it work, but it comes out really sloppy and I'm getting 2 cast on stitches with each maneuver. Jan's link is to the one I've always used and it really works well.