So I apologize in advance for the image not being organ related. it's what I had handy, and is related to what I do the rest of the time.
The original image was 3273x2182. I imported the image into my photo app (Adobe Lightroom), adjusted exposure and exported a copy of the image to my desktop
specifying the width to be 640px. I browsed to Flickr and logged in. I uploaded the 640px version of the photo to my Photostream, and then "shared" it. One of the sharing options is BBcode. I copied the HTML/URL it gave me, and pasted it into THIS post. Total time — I don't know. Almost nothing. It took a lot longer to type and spell check this post than it did to post the image.
IMG_9099-3 by
GrantHY, on Flickr
The slight downside is that Flickr also puts up other identifying information related to the photo and my public Photostream, but that can be quickly edited out. I was in a hurry and didn't do it.