Open word dokument, refill placeholder and display individual text

I want to open a word document with includes placeholders which have to be filled out with name, adress, etc of a person. So when opening the word file a message box should ask about this data and fill in the placeholders.
In the next step a message box should ask for a grade. For example, grade 1 stands for text 1, grade 2 stands for text 2, grade 3 stands for text 3 etc.
Can somebody explain me how to coding? It´s my first time using this programme.
Thanks a lot.