I backup the MySQL database every day, and just wondering if the Chevereto front-end host crash, and then I re-install the Chevereto, how can I import this backup database?
To restore a dabase backup you will have to follow the indications of your hosting environment. If you have cpanel then refer to cpanel docs, if you don't use cpanel you will have to issue a mysql backup command via ssh console.
Please note that the database only stores data. Images are stored in the file system and at app/settings.php the system stores the database connection information.
Also, do please keep in mind that the database is part of your server and we don't provide server support.