This video will help you learn how to add a new color of yarn when knitting. This skill is used for most color work techniques and is much easier than it might seem. It is useful for doing stripes, fair isle, and even can be used to add a new ball of yarn when you run out.
There are no steps for this technique. Basically you want to hold your new contrasting color (CC) of yarn the same way you would your main color (MC) of working yarn and work your pattern with it. It might help to work the tail of the yarn with the working part of the yarn for a few stitches to secure the end so it isn’t too loose as you continue in your pattern.