Key Lime Baby Blanket Help!

I am trying to make this baby blanket from Creative Knitting Magazine, the January 2009 edition. I do not understand about the using 2 different yarns. Some rows you use A, and some you use B. This is what the pattern notes says, and where I do not understand what to do with the yarn?? ‘Blanket is worked back and forth on circular needle to accomodate large number of stitches. Carry color not in use up the side of the work.’ That totally floors me, I have no idea whsat carry the color up the side means???
Thank You.

It just means that you shouldn’t cut the yarn when you change colors. You wouldn’t want all those ends to have to weave it.
Work across the rows, then just bring the new color up and start knitting with it, leaving the other hanging, waiting for it’s turn.
If you’re working more than 2 rows, you can try to make sure to bring the color you’re working under the one hanging on the side to help hold it next to the side to prevent a loop.

Thank You. I kinda thought that is what it meant, I wondered about all of the hanging threads, and I am sure when I do it, it will make more sense to me!!! Thank You again!!