test.cs

// load the document part names from the spreadsheet document
var documentPartNames = LoadSettings.GetDocumentPartNames("spreadsheet.xlsx", StreamType.SpreadsheetML);

// load the first sheet
var ls = new LoadSettings() {
  DocumentPartName = documentPartNames[0]
};

var dataStructure = "";

// handle the TableCreated event
textControl1.TableCreated += (sender, e) => TextControl1_TableCreated(out dataStructure, sender, e);
// load the document
textControl1.Selection.Load("spreadsheet.xlsx", StreamType.SpreadsheetML, ls);

Debug.WriteLine(dataStructure);