Sorry you didn't get your question answered sooner...
You can just start knitting with the new yarn, and then weave in the end later, following the path of another strand of yarn for a few stitches, or hiding it in the selvage stitches over a few rows.
Or, you can cheat a bit and save time:
thread the end of the new yarn through the stitch below the first stitch, then double up the working yarn with its tail end, and knit a few stitches with both strands together. This will work in the tail of the yarn, and later you can just cut it.
If you're doing a scarf, the disadvantage with all these methods is that the tip of the tail-end might pop out and show. To avoid this, you could use the method I just described, but hide the tail end in the working yarn before knitting with it, either by doing a Russian join, or by felting it to the working yarn. (See "Joining Yarn" in the Basic Techniques/More sections.)
Hope this is clear!
KnittingHelp Queen Bee
"There is a vitality, a life force, an energy, a quickening that is translated through you into action, and because there is only one of you in all of time, this expression is unique. And if you block it, it will never exist through any other medium and it will be lost. The world will not have it. It is not your business to determine how good it is nor how valuable nor how it compares with other expressions. It is your business to keep it yours clearly and directly, to keep the channel open. You do not even have to believe in yourself or your work. You have to keep yourself open and aware to the urges that motivate you. Keep the channel open."
— Martha Graham