Scripting Index has sometimes very good examples
In this case if you want it to open on Desktop, you can use $DESKTOP path variable
Names Default To Here(1);
New Window("File explore",
<<modal,
Spacer Box(size(20, 10)),
Text Box("Choose a log.txt file:"),
BB1 = Button Box("Pick file",
D = Pick File("Select file", "$DESKTOP");
If(D != "",
file1 << set text(D)
);
),
file1 = Text Box(),
);
-Jarmo