How to Knit a Scarf

Great idea!
Scarves can be as simple as gathering needles and yarn, casting on some stitches, knitting them until it's scarf length, then casting off.
How to? Well, there are many great sites but I like Lion Brand Yarns because:

• Their yarns are readily available at the big chain stores - great for beginners.
• They provide volumes of help ... here's "Learn to Knit"http://learntoknit.lionbrand.com/

Might I suggest that you do a bit of practice with a worsted weight wool (that's just kind of a regular weight, it will have a number 4 on the weight part of the label) Something like this:http://cache.lionbrand.com//yarns/lionWo...in a light color so you can see your stitches easily. Use #8 or #9 needles ... they're about $5 so you may want to try wood and metal to see which you like best.
Just cast on 20 stitches or so, knit, turn, knit ... count your stitches at the end of each row to make sure you're not adding or dropping any stitches ... when it's coming out relatively even, you're ready for the scarf.
I would suggest a chunky yarn for your first scarf ... like Lion's Thick & Quick with either #13 or #15 needles. It can be a bit unwieldy to work with BUT it works up quickly. Don't forget that 5 or 6 feet of scarf is not a tiny project. You'll be glad about the 3 or 4 foot mark that you've chosen a bigger yarn/ needles!

Happy Knitting!