You can do this on serverside:
- First of all you have to find your placeholder (div, form...)
- You can make a new LiteralControl, for example <img> tag.
- Now you can add to your form the image.
You can add dynamically LiteralControl to your website as the follows.
Control myPlaceHolder = FindControl("form1");
String imageLink = "picture.jpg";
String yourPicture = "<img src=\"" + imagelink + "\" alt=\"pictureAlt\" />";
myPlaceHolder.Controls.Add(new LiteralControl(yourPicture));