You could just knot the yarn, if you like, but it might be neater to leave a bit of a tail to weave in. If you do tie a know, try to do it so it won't show.
With the neck opening... You've got 39 stitches connected to 1 ball of yarn (well say ball 1) on your right needle, then some bound of stitches, and 39 stitches on your left needle... Just attach a new ball (ball 2) , and work the rest of those 39 stitches. When you've finished thatrow, turn your work, and keep knitting (or purling, or whatever th pattern says) with ball #2. Then when you egt to the bound off stitches, skip over to the other 39 stitches and knit them with ball 1, which is already connected. Then, turn, knit with ball1, skip the BOs, knit with ball 2...
The pattern tells you to do both sides at once with seperate balls, so that both sides will be the same length when you're finished. Hope that Helps! You can start a blog in the "blog threads" forum OR start a new topin in general (or wherever!!) and post pics of your progress. Good luck!