I like to use Quia a lot for student practice. When I taught Algebra this was very efficient as I mostly had to type the questions. The problem with Geometry is it has so many darn pictures!
Here is how I get images into Quia (or any other place that I would want to put pictures).
In the bottom right corner is a little triangle that you can grab to resize the canvas.
The problem with resizing the canvas is it changes the size of your drawing, notice it is now huge. The canvas is a piece of paper so if you make the canvas larger your drawing will be scaled so that it will print on a piece of paper. If you make your canvas smaller it will resize the drawing so it will print out on a piece of paper. I do not actually want a huge drawing in my activity, but there is a way around this.
From the drop down list choose SMALL drawing so that when you link to the drawing it is a normal size and not huge. Copy the embed code. (note the embed code changes when you switch from medium to small so select the small size and then copy).
You can then paste this embed code into any place that accepts html code.
Change to public on the web.