The beta can be downloaded from your client area, just under the main download button. If upgrading an existing community you can also use the automatic upgrader if you wish.
If you haven't already, create a constants.php file and add the following line:
<?php
define( 'USE_DEVELOPMENT_BUILDS', TRUE );
Then go to AdminCP → System → Applications and click Check for Updates, and the beta will become available for you to upgrade in the normal way. Your community will show you all future betas while that line is in the constants.php file.
Important Information
Possible Bugs
We consider beta releases generally safe to use on a live site, but, as a beta release, there will probably be undiscovered issues. Any issues on your community during the beta stage may not be fixed until a future release. We will usually not specifically address any individual issues on your community. This means you will have to wait (sometimes several days) for a new release to get fixes.
Backup
You must maintain a backup of your site and know how to restore a backup if needed. If a beta causes major problems we cannot guarantee a fast resolution so you need to be ready and able to restore a backup if necessary.
Support
For general issues please use the beta releases bug tracker. If our staff need more information on a bug report from you in private, they will reply to the bug report and ask you to submit a ticket referencing the report. For more important or private issues please submit a ticket noting you are using the beta.
In short, we will fix issues that come up but it may take longer than normal. Sometimes an issue may require you to restore a backup. Do not use a beta if you cannot handle waiting a few days between releases for fixes or restoring backups.