As well as yarn, you also need needles, usually a pair, in the appropriate size for the yarn. The size of a needle is the metric measurement taken round its shaft. Needles of the same size can vary in length. Choose the needles according to the width of garment being made so that the stitches are held easily.
The needle size is specified in the pattern you wish to follow, but you may well find you need one size smaller or larger to knit to the correct tension.
Hold the needle with the stitches to be worked in your left hand and the one which forms the new stitches in your right hand, wind the yarn over the fingers as shown to control the tension. When forming the stitch, carry the yarn round the needle point with the right hand index finger while still holding the needle.
Special needles are made with points at each end, in sets of four, for making a circular fabric without seams, or in short lengths for cabling.
You may also require a stitch holder for reserving certain stitches while you work on others.
For sewing up finished garments, use a blunt-ended yarn needle.