Into each of the six stitches in your initial row, but an increase stitch. Or, put another way, put two stitches into each stitch. This should result in twelve total stitches. Then follow the pattern below starting with row three to reach a closing circle of twenty-one stitches. Then daisy chain for storage and set this aside for later joining to the main part of the ball.
Row / Pattern
1. 6 single stitches
2. inc inc inc inc inc inc (12)
3. 1 inc 2 inc 1 inc 2 inc 1 inc (17)
4. 2 inc 3 inc 3 inc 3 inc 2 (21)
key:
1 = one single stitch
2 = two single stitches
3 = three single stitches
inc = one increase stitch, or two stitches crocheted into the same stitch