Pattern help. New crocheter

Please help me What does dc in the top of the turning chain mean?

Here is pattern. I think I messed up. It is not making even holes as I am doing it. Do I attach the big rectangle to the sc chain first. I attached the small and it does not seem r ight
Can't I just make 2 rectangles, join them and the sc the neck opening?

http://www.lionbrand.com/patterns/cjif-monsterInLawPoncho.html?noImages=

As to your first question "What does dc in the top of the turning chain mean?", in the previous row you worked some chains to bring your crocheting up to height. This is called the turning chain. The pattern is telling you to work your dc in the top chain.

As to your second question, why don't you just sew the two rectangles together and see if you like the effect. If you do, then you're done.