How to select Language in a Encoding DotNET NAV Object

Hi guys.. I'm developing a report and I need select a language to work. How i can do it.. thanks.

This is my code:

StreamReader := StreamReader.StreamReader(InStr, Encoding.Unicode);
....
StreamWriter := StreamWriter.StreamWriter(OutStr, Encoding.Unicode);

FOR I := 0 TO STRLEN(linea) DO BEGIN
Char := COPYSTR(linea, I + 1, 1);
InStrFieldValue := InStrFieldValue + Char; //Char is a Chinese character i need a Spanish char
IF Char = ';' THEN
BEGIN
FillField(num_campo, InStrFieldValue);
num_campo += 1;
END;
END;