So, you know how to cast on now, I bet you're simply itching to know how to start knitting. Oh, all right then, I'll tell you.
With the needle with all the stitches on it in your left hand, take your right needle and thread it through the first stitch, so it's behind the left needle.
Wrap the wool from the ball around the right needle and pull the stitch on the left needle over onto the right. Did I explain that okay? Try YouTubing it!
It should look like this when complete.
Repeat this process and your first row should look like the above photograph.
Keep going and going and going some more and you'll get something like this! Soon you'll have a scarf on your hands!