Training can be found here.
Make it Official
Train to be a certified WCSL Starter, Referee, and/or Stroke & Turn Official using the WCSL training program created by Head Official, Josh Hesse.
Along with this training, you will need to do the Swimmingly Training which you can find a link to above.
Please note that the WCSL training may contain some items about Swimmingly that have changed, but the basics of the job as an official should still be the same.