Crocheting with 2 strands is an easy way to either make a piece thicker or to combine 2 colors in a unique way.
To crochet with 2 strands of yarn at the same time, all you have to do is crochet just like normal, but with 2 strands!
I like to start by lining up my ends of both strands and creating a slip knot. Then, I just crochet like normal. I go a little bit slower because you want to make sure you are pulling through both strands (and not splitting the strands at all) when you are crocheting.
Lousy Llama 