Joining on circular needles

I have cast on 202 stitches. The next instruction is to join and plac marker for beg of rnd. How do I join?

You just begin knitting. Hold the end with the yarn going to the ball in your right hand, put the marker over the needle and knit the first stitch on the left needle. Give it an extra tug to take up any slack at the join, and knit the next couple stitches a little tighter too.