FileMaker scripts use a very basic straight forward structure similar to may structured programming languages such as visual basic, Pascal, C++ and others. It has If Then Else, looping, and subroutine call capabilities not terribly different from these.
It also functions in ways quite different and pretty much unique to FileMaker. When designing scripts, for example, you have to keep track of what layout and what record on that layout is 'current' as the layout establishes what table and what record is directly accessible to your script at any given point in its execution. This will be different from working with "objects" and "collections" in Visual Basic, for example.
Knowledge of SQL can actually be a handicap for some developers as FileMaker does not directly use SQL and the equivalent processes can be significantly different when querying the database, sorting records, setting up a conditional value list etc. Developers with such experience often express some frustration here in this forum when they find that SQL based methods familiar to them don't work in FileMaker. They have to "unlearn" SQL even as they learn FileMaker in some cases.
There are a number of traiing and reference resources available to you (though perhaps in English rather than danish in some cases), that you can invest time and effort in.
If this database were to be published to the web, PHP might be useful if you select custom web publishing as your method for accomplishing this.