b2evolution upgrade to 2.4.5 + mysql bak

Backup your database:
mysqldump -umyname -p b2evolution > dumpfile.sql

Backup your b2evolution folder, copy and paste should be ok.

Then: from /b2evolution/doc/upgradefrom_b2evo.html

Upgrading from a previous version of b2evolution

Before you begin, please note that some network features of b2evolution require you to agree our simple Terms of service.

1. Backup all your b2evolution files. Take special care of the files you may have modified, including /conf, /skins, /plugins, your /media directory and possibly stubfiles, hacks or custom templates...
2. You should also backup your database if you can. This functionality should be provided by your host.
3. If you are upgrading from a version prior to 2.0, we highly recommend you clean up outdated files. To achieve this, delete your b2evolution folders except /media. Folders to delete include /admin, /conf, /cron, /htsrv, /inc, /install, /plugins, /skins, /skins_adm, /xmlsrv. Depending on your version, you may not have all of these folders on your server. Also, again, make sure you have a backup before deleting.
4. Upload all new b2evolution files from the /blogs folder to your site. We cannot stress this enough: ALL FILES! And that means you cannot reuse your /conf files, default skin templates or default plugins as they are.

Since your custom skins and custom plugins should be using different names, they will not be overwritten. Same for your media files.

The one file you must absolutely restore from your backup (see step 1) though is /blogs/conf/_basic_config.php. You will need to either restore or recreate that file in order to proceed with upgrade.
5. Run the installation/upgrade script on your server. It is located in http://yoursite.com/yourblogsfolder/install/ . Then, simply follow the on screen instructions.

The installer/upgrader will allow you to run a database upgrade from any b2evolution version to the new one.
6. Check to make sure the new installation works.
7. Check the online manual for specific upgrade instructions to your new version of b2evolution.
8. On production servers, it is recommended that you delete the /install subfolder.
9. If you had hacks or other customizations to the core files, your can bring those back now. We recommend you get yourself a diff/merge tool like WinMerge. This will allow you to easily compare your old (backuped) files with the new files (even whole directories at once) and report changes accordingly.

The next step is to upgrade the skins..