Hey Sowmya,
Add the png file to the solution in a folder, name it as Images. Edit the properties of the png file as: Enable the Copy to Output Directory option. Further enable it for the Images folder too.
then add the below code or similar. It should work for you.
PictureBox picture = new PictureBox
{
Name = "pictureBox",
Size = new Size(50, 50),
Location = new Point(10,10),
Visible=true
};
pic.ImageLocation = "..\Images\picture.jpg";
Form1.Controls.Add(pic);
hope it helps.
-anurag