The new beta is available through the Mac App Store as an over the air update for beta testers with their Mac enrolled in the program. Those wishing to join the program can sign up on Apple’s beta testing website.
Mac Rumors has shared details about the new beta and what to expect when the commercial release comes out:
It’s not yet known what improvements the latest update to OS X El Capitan will bring, but it’s likely to include bug fixes, security enhancements, and performance improvements to address issues discovered since the release of OS X 10.11.1. Apple’s release notes for the first developer beta asked testers to focus on Graphics, Wi-Fi, Calendar, USB, Notes, Photos, and Spotlight.