Backend development

The work to be done is explained in this link: https://unicorn.artheriom.fr/#/techno-ws-l2
The topic is in french, feel free to use this translator: https://www.deepl.com/translator
Please click on the "second partie" heading, all the work to be done is explained there.
Please ignore the "version of the dead" since we don't have to do it.

the skills needed:
we have to use Java Spark to manage our web server and FreeMarker to templatize our HTML pages. To store the data, we will use an H2 database, and we will access the database with the native JDBC driver of Java.

You will not do it from scratch since I have the folder with code provided, you have to download it and add the code to make it functionnal.
this is the link to the folder:
https://drive.google.com/drive/folders/1FfKLeejXbCmjTm0_AU-hQ9G6nbih6-e0?usp=sharing

Important: the uploaded picture is the data base structure.
Please don't forget to explain to me what you have done, since the purpose it to do it and help me understand it.