Knitting Instructions for Knitting Two Colours Simply

I found a great simple little article at www.diynetwork.com/diy/na_knitting/article/0,2025,DIY_14141_4357739,00.html
on how to knit with two colours without having to tie knots in the threads and so avoiding my problem of incorrectly guessing the amount of yarn (that's a technical term I believe) required to finish the row before changing colours.

Introducing color-knitting techniques whose degrees of difficulty range from beginner to intermediate, Melissa starts off with two types of stripes, bands of color and random patterns, and moves on to a bicolored mosaic pattern. Finally, she completes the rainbow lesson with a complex and luscious Fair Isle pattern.

Carrying Colors

Smart Knitsters (those who have better things to do than tidy up yarn tails) are going to want to learn why Melissa always tries to use even--rather than odd--numbers of rows for each stripe: When you use even numbers of rows between colors, the next time you need to knit with a color of yarn, it will already be in position (on the correct end of the work) for you to begin knitting. This way, you can "carry" the yarns up the side of your work instead of breaking the yarn, which creates more ends to weave in.

The best way to begin the new color (hint: it doesn't involve knots) is simply to get to the end of the row, turn your work and begin to knit the first stitch. Instead of wrapping your working yarn around the needle, pick up the new yarn color and wrap it around your right needle. Be sure that you don't pull the new color too tight; your fabric will pucker if the carried yarns aren't left loose enough.