To knit a scarf, you will need:
Knitting needles: Choose needles that are appropriate for the weight of your yarn. For example, if you are using a medium weight yarn, you might want to use size 8 or 9 needles.
Yarn: Choose a yarn that is appropriate for the type of scarf you want to knit. For example, if you want to knit a warm and cozy scarf, you might want to choose a wool or alpaca yarn. If you want a lighter, more drapey scarf, you might choose a cotton or linen yarn.
Scissors: You will need a pair of scissors to cut your yarn when you are finished with your scarf.
A tapestry needle: This is a large, blunt needle with a large eye that you can use to weave in the ends of your yarn when you are finished with your scarf.
To start knitting your scarf, you will need to cast on a certain number of stitches. The number of stitches you will need will depend on the width of your scarf and the gauge of your knitting. For example, if you want to knit a scarf that is 8 inches wide and you are knitting with a gauge of 5 stitches per inch, you will need to cast on 40 stitches.
To knit your scarf, you will need to work in a simple pattern of knit and purl stitches. For example, you might want to work in a "garter stitch," which is created by knitting every row. Or, you might want to work in a "stockinette stitch," which is created by alternating rows of knit and purl stitches.
To finish your scarf, you will need to bind off your stitches when you have reached the desired length. To do this, you will need to work the stitches as you normally would until you have two stitches left on your right-hand needle. Then, you will need to insert the left-hand needle through the first stitch on the right-hand needle and lift it over the second stitch. You will then have one stitch left on your right-hand needle. Repeat this process until you have bound off all of the stitches.
When you are finished, you can weave in the ends of your yarn using a tapestry needle. Then, you can block your scarf if desired to even out the stitches and give it a more polished appearance.