When you are working the Brioche Stitch in the round you alternate between a Brioche Knit round and a Brioche Purl round.
To work the brioche purl round you will work a brioche purl (brp) stitch and then the next stitch is slip one, yarnover (sl1yo). These two stitches are repeated to create the round.
You can find the video for the brioche knit round here.
Brioche worked flat in rows in shown here.
This is how to work the Brioche Purl round:
Read our Knit Basics Purl Stitch Tutorial