Here's what I do.
Click on POST NEW THREAD.
When it opens, type your subject and message.
Then, scroll down the page until you see MANAGE ATTACHMENTS. Click on it and a new window will open.
In the new window I click on BROWSE under UPLOAD FILES FROM YOUR COMPUTER.
Find your pic, open it, and then click UPLOAD.
It takes less than 1/2 minute for mine to upload.
When the pic is uploaded, you will see CURRENT ATTACHMENTS and the picture name or number..
Click on CLOSE THIS WINDOW...at the bottom. This will bring you back to the original window.
Don't forget to scroll down and click SUBMIT NEW THREAD.
This works for me.
If your pic is too big it may not post and you may have to resize it.