First thing's first: make sure you have all of your supplies. You'll need a 5.5mm afghan hook (it must be an afghan hook, regular ones aren't long enough for this project), and one regular 5.5mm crochet hook, 6-7 7 oz skeins of your main color, and 2-3 of your coordinating or accent color. When it comes to yarn, it's best to use one with no dye lot (it will say that on the paper around the yarn) in case you need more, you want to make sure you can get the same color.
Now, the knot. Take the end of your string, and fold it over, like so:
When you have made your 223 rows, you'll finish it off by doing a single crochet across the top. A single crochet works like this: Make a loop like usual - you should have 2 loops on your hook.
Repeat the process of making a loop, hooking your yarn, and pulling it through the two loops until you have made it all the way across. When you have finished, just make a loop through a piece of yarn at the end, then cut the loop in the middle, and pull the rest of the yarn away from your panel. Congratulations! You've just made most of a panel!
The next installment will be finishing off the edges and creating a design on your panel.
To make an entire afghan, you will make 4 panels of 24 stitches across and 223 rows long, and one panel that is 42 stitches across and 223 rows long. In the end, you'll crochet them all together (more on this later).