If you’re not familiar with the concept of UNIX File Permissions, please see this tutorial: UNIX Directory and File Permissions.

Cheat sheet: if you want to try & quickly muddle through, try to set the following permissions (no guarantee of success nor security):

• set 0666 on /conf/_basic_config.php which should allow the installer to be able to automatically update your config based on your input.
• set 0777 on /media/ and all its subfolders in order to upload images and other media from b2evo’s backoffice.

For deeper information, please see:

• Directory And File Permissions
• Media File Permission Errors
• Optimal File Permissions
• Security