To post an image click Reply
Do not simply go to the bottom of the thread and use Quick Reply
You have to click the Reply button on one of the posts.

Then, right under the text box where you type your reply you will see 'File Manager'
If you click that it lets you browse your computer to find a file. Then click Add Image (or close) to officially add it.
Then click Done ..

The whole trick is knowing where to find it, and you have to click Reply to get there.

I do not work here, but the benefits are still awesome
Make your sound your own!