Well, you know, ASP.NET uses HTML to "render" to the client in the web
browser so you have a couple of options:
1) Generate the HTML code to draw a rectangle.
For example (ASP.NET)
Response.Write("<table width=200 height=200 bgcolor=red><tr><td>
</td></tr></table>");
2) Create an image on the server and include an image tag reference to it in
your ASP.NET page.
For example (ASP.NET)
CreateRectImage(filename);
Response.Write("<img src=filename>");
K