import name, lastname, gender from file

[sunshinebard]

(newby)
hi there.
I have a text file that changes it's data often (it is an export file from a program), it contains:

lastname: Miller
firstname: John
gender: 3

I want to insert in thunderbird something like "dear Mr. John Miller"
so far I think I need [[FILE=C:\infos.txt]] and maybee Java. but output doesn't work:

var Input = "[[FILE=C:\infos.txt]]";
return (Input);

that works for testing:
var Input = "test";
return (Input);

how can I process the content of that file?