Hi pierjsap,
The ASCII file reader uses regex to parse values by line of the input.
There is good information in context help for the data file data source as to how to use it. That's the blue question mark by the data source name while you are editing it.
In brief, you have to implement a Java class that extends the abstract importer you wish to use. These threads have examples:
https://forum.infiniteautomation.com/topic/1636/problem-with-defining-class-for-csv-datafile-import
https://forum.infiniteautomation.com/topic/3126/file-datasource-breaks-on-file-upload
We can work through the CSV you need to import in this thread, if you'd like.
Another option that has come up in the past is reading the CSV from a scripting data source, as in this thread: https://forum.infiniteautomation.com/topic/2970/is-it-possible-to-read-several-csv-documents-by-scripting