WorldKnit.com has some great tutorials if you're in a bind. They even have an area for those wishing how to learn garment design.

Stuff you’ll need:

• waste yarn in a contrasting colour, preferably same weight as project yarn
• set of smaller needles (smaller than required for the pattern)

Method:

Look at the pattern to see the number of cast on stitches. Using waste yarn, cast on 1/2 the required  number of stitches. (If pattern calls for odd number, then cast on 1/2 the number of required stitches + 1).

1st row: Purl to end

2nd row: Knit to end.

Join in main colour yarn. Cont in stockingette st for 4 more rows so that the purl side is facing.

P1. Look down the four rows to the contrasting yarn and you’ll clearly see your project yarn as “purl bumps”. With your left needle, you will pick  up the first bump in the row, four rows down from where you have just purled. Knit into the back of this picked up stitch. Purl the next stitch; with left needle, pick up from 4 rows below, knit into the back of the stitch and so on. Cont in this manner to the end of the row. When you finish your last purl stitch, you’re not finished.  There is still one more to pick up and knit, although you may not see that. The end of the row is basically a knot. Just shove your needle in there and knit into the back for that final stitch.

Now you may remove the contrasting waste yarn as it is no longer needed. You can cut the contrast yarn, just don’t cut  your project yarn! Now, if your pattern calls for a 1 x 1 (K1, P1) rib, then you’re off to the races and you can ignore what comes next.

For anyone needing a lovely 2 x 2 rib, like I did ——> follow me. Here comes the tricky part. You now have to twist every other stitch. Just like cabling. In fact, I use a cable needle to bring the knit stitch forward. I do this as I go as well. So I’ll purl, then twist, then purl, then knit, then twist…. and so on. All of this may seem like a major pain in the ass, but  once you do it a couple of times and once you see the fruits of your labour,  you’ll feel triumphant! One side of the 2 x 2 rib, in the first row will look slightly wonky, but no matter, that’s the backside. Yay! I’ll post tutorial photos when I get a chance. I promise.