Stripes when circular knitting

I have picked up knitting needles again after almost 20 years and am really enjoying it. My second project was a hat for my son- pretty simple, until I wanted to add a stripe. I was using circular needles, and the stripe seems off at the beginning by one stitch. I followed a relatively simple technique for flat striping, but it is starting to dawn on me that adding a color stripe with circular needles is different. Any pointers?

Thanks! Linda

I love the TechKnitter.

Thanks so much for the help and the site- looks great! (Can’t believe that I’m becoming a knitting fanatic, but it does seem to be happening!)