Anoop,
You said you could create a document using OpenXmlSdk. With this in mind, you can use the following code to create a content control to add your document to the Wordprocessing.Body element.
Run run = new Run(new Text("Insert any text Here") { Space = StaticTextConstants.Preserve });
Paragraph paragraph = new Paragraph(run);
SdtProperties sdtPr = new SdtProperties(
new Alias { Val = "MyContentCotrol" },
new Tag { Val = "_myContentControl" });
SdtContentBlock sdtCBlock = new SdtContentBlock(paragraph);
SdtBlock sdtBlock = new SdtBlock(sdtPr, sdtCBlock);
WordprocessingDocument wDoc = WordprocessingDocument.Open(path, true);
Body mBody = wDoc.MainDocumentPart.Document.Body;
mBody.AppendChild(sdtBlock);
wDoc.MainDocumentPart.Document.Save();
wDoc.Dispose();
, . , , " XML". , CustomXmlBlock ContentControl ?