Answer by Arul for C# StringBuilder : i can't set a specific Microsoft Word line feed

Seems like you need to use "InsertParagraph"

Paragraph p1 = document.InsertParagraph();
p1.Append("New Para 1");

Paragraph p2 = document.InsertParagraph();
p2.Append("New Para 2");

Paragraph p3 = document.InsertParagraph();
p3.Append("New Para 3");