Make a backup
From b2evolution manual
This manual page is outdated. NEW PAGE: Make A Backup in b2evolution v5+.
A b2evolution blog is made up of two distinct parts: the b2evolution program files (which includes your site layout, the backoffice, etc.) and your MySQL database (which contains all your posts, comments, users, but not your uploaded files/images).
When most people speak of backing up their site they are primarily thinking of the posts and comments in their database. Backing up your database is not done through b2evolution. You can do so through the tools your webhost has given you access to, such as phpMyAdmin, cPanel, or something similar. Export your b2evolution database to a file and then you can save it as a backup or reuse it elsewhere.
Keep in mind that any files or images that you upload with your posts are not stored in the database. They are kept in the /media folder and refered to by b2evolution. You should also backup your /media folder in order to keep your file and image links working if you need to reinstall or restore your blog.
If you want to backup your site's design/layout you can simply save the skin folder that you are using.
If you want to backup the particular hacks or changes you've made to your b2evo installation then you will need to backup any files that you have altered.
b2evolution versions 2.2 and later
The database table that contains the text of your posts is named 'items__item'. It's no longer called 'posts' because it also contains the text of your pages, links, and even new Types that you make up.