Adding crochet borders

[nkirksey]

I just finished knitting my first sweater. The pattern calls for two rows of dc on the bottom of the sweater body & on the bottom of each short sleeve. I've learned how to crochet & how to do the dc stitch, but can't figure out how to add the border. Do I need to do a chain first or use the existing bottom of the sweater instead & just pick up the stitches as if they were a chain? I also can't come up with a way to add the 2nd row of dc. HELP!! Thanks in advance.