using Spire.Presentation;
using System.Drawing;

Presentation presentation = new Presentation();
presentation.LoadFromFile("sample.pptx");

ICommentAuthor author = presentation.CommentAuthors.AddAuthor("E-iceblue", "comment:");

presentation.Slides[1].AddComment(author, "This part is pretty important. Please pay attention to it", new System.Drawing.PointF(42, 4), DateTime.Now);

presentation.SaveToFile("PPTwithcomment.pptx", FileFormat.Pptx2010);
System.Diagnostics.Process.Start("PPTwithcomment.pptx");

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Spire.Presentation;
 
namespace PPTComment
{
  class Program
  {
    static void Main(string[] args)
    {
      //create PPT document and load file
      Presentation presentation = new Presentation();
      presentation.LoadFromFile("sample.pptx");
      //comment author
      ICommentAuthor author = presentation.CommentAuthors.AddAuthor("E-iceblue", "comment:");
      //add comment
      presentation.Slides[1].AddComment(author, "This part is pretty important. Please pay attention to it", new System.Drawing.PointF(42, 4), DateTime.Now);
      //save the document
      presentation.SaveToFile("PPTwithcomment.pptx", FileFormat.Pptx2010);
      System.Diagnostics.Process.Start("PPTwithcomment.pptx");
    }
  }
}