// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_LoadingAndSaving();

// Create an object of the Document class
Document doc = new Document();
// Initialize Page class object
Page page = new Page(doc);
// Initialize Outline class object
Outline outline = new Outline(doc);
// Initialize OutlineElement class object
OutlineElement outlineElem = new OutlineElement(doc);

// Initialize TextStyle class object and set formatting properties
ParagraphStyle textStyle = new ParagraphStyle { FontColor = Color.Black, FontName = "Arial", FontSize = 10 };
// Initialize RichText class object and apply text style
RichText text = new RichText(doc) { Text = "Hello OneNote text!", ParagraphStyle = textStyle };

// Add RichText node
outlineElem.AppendChildLast(text);
// Add OutlineElement node
outline.AppendChildLast(outlineElem);
// Add Outline node
page.AppendChildLast(outline);
// Add Page node
doc.AppendChildLast(page);

dataDir = dataDir + "CreateDocWithSimpleRichText_out.one";
// Save OneNote document
doc.Save(dataDir);