Need info on how to upload screen shots to Ask a Question

I would like to upload screen shots to facilitate your answering my question at WPMU Support. Simple question, how do I do that? I have tried dragging the image to the Ask a Question box I’m writing in, but no luck. I have also tried to copy and paste, but I just get a reference to the image, like this:

Screen Shot 2013-1.png

Please help. And thanks in advance for your prompt reply.