Take the spare needle (blue) in your right hand and hold needle one (pink) in your left. Insert the blue needle into the first stitch and, pulling the yarn tight from the back, knit it as normal. Knit every stitch on this needle.
When you reach the end of needle one, the stitches will have transferred to your blue needle. The pink one is now your spare needle and will be used to knit the stitches on needle two (yellow). Knit all the stitches on this needle.
Continue in this manner until you reach the marker, slip the marker and finish the round.