First, save it as a PNG or GIF (PNG is better), then, host it at a free online photo storage site such as
Photobucket or
Imageshack. Then right click the image, go all the way down to Properties, click it, highlight the Address (URL) and copy it. Go to ZU, hit the "Add Image" button, paste the URL onto the... thing... and it should be wrapped in IMG tags. Then it should show up on your post. Hope that helps.