Shoulders and Joining Yarn
The back is complete and the instructions say to bind off the stitches. After you finish the fronts you will be told to sew the front and back together. Once again we will deviate from the written instructions here. I put my back section on a stitch holder (otherwise known as a spare, smaller circular needle) because I am going to do a three needle bind-off when I am ready to attach the front and the back.
Why on earth would I bind them off and then have to sew them together???
It is MUCH easier to do a three needle bind-off and it gives you about the same amount of stability. Excellent photos of how-to here. If I wanted an invisible flow over the shoulders I would do the Kitchener Stitch, but it doesn't provide any support.
Next the instructions tell me to attach a ball of yarn to each side of the front and work both sides at the same time. As a lazy knitter, there is no way I am going to mess with two sets of needles and four balls of yarn (because I am using two yarn together.) I am going to work each side separately and COUNT to make sure I have the same number of rows.
To join a new yarn for working on the fronts I simply take the end of the ball and start knitting with it. You may tie it to the side with a loose knot if you like - not tight because you will find later on that the place you tied itis much looser than you thought and you will want to redo it, not to mention, when you are done, you will want to pick out the knot and weave the end in.
In my experience, the best way to weave the end in is to use it to duplicate stitch on the BACK of the garment. It is truly invisible this way.
And re: the problems people are having with the Comments and Links - it is definitely an issue with Mozilla - I can see that it is happening but I have no idea why. Mozilla appears not to be able to "see" that type of file.