todo
For developing on the backend you need a php Webserver and a Mysql database running. You can use a docker image which provides this feature. For example this one (assuming you are currently in the root directory of this repository):
docker run -d -p 8080:80 -p 3306:3306 -v $PWD:/var/www/html mrxder/docker-apache-php7.2-mysql-phpmyadmin
Now you can load the default database schema which you can find in backend/dev_db.sql. To do this you can use phpmyadmin which you can reach over http://127.0.0.1:8080/phpmyadmin. The default login is devroot:123.