Theres a sticky on how to do it. But I thing its by uploading it onto photobucket and once its there get the url of it and click the add image button on the reply to thread where you type and enter the url into the box that pops up. I'm not completely sure as I have never posted pictures on here and have never read the sticky. I hope I was right and I helped in a way.
Once it is hosted, highlight the contents inside of the box labeled "Direct Link to Image" and press Ctrl+C
Go to Sythe, open a post, type
If for some reason the image doesn't show up, you can post the link too, so people will be direcdted to your image when they click it.
You're welcome.
Note: If you'd like to block out anything, after pressing Ctrl+V in paint, click on the paint brush button and then click on the black paint. Cover anything you don't want to be seen. Continue with the steps.