You're good like that but if you want to embed the images you need to use a 3rd party image hosting site like imgur. The embed feature is turned off as it's too bandwidth intensive and would be too difficult for us to moderate.
You can also create an account at Heatware, then you can link profiles and payments methods preferred. When selling on classifieds and Reddit it gives people some assurance as a trader they also will host images of the trade.
Try here since the classified traffic Toms has slowed with the update to the forums.