Hello Carole,
Are you trying an e-wrap cast on? If you are, hang the comb after you have wrapped the needles, then use a tension appropriate to your yarn to knit with.
Make sure none of the buttons at the front of the carriage are pressed in and the Holding Cam Lever is on 'N'. The needles should then knit back to 'B' as you knit the row.
If you want a simple cast on, push forward alternate needles to 'B' position and knit 1 row to the left on a tightish tension. Hang the comb on to these loops.
Push forward the in-between needles, so that they are all in a straight line, change the tension to suit your yarn and knit back to the right. You should now be able to continue knitting.
Hope this helps you to get started,
Sue
February 2010