For Premium Members it's easy since you have Upload capability.
1. When creating or editing a post, below the message box you will see a Button "Upload a File", click that.
A Browsing window will come up and you can navigate to the Photo on your computer.
You will then see the Photo...
There is an issue with Uploading Photos (attachjments). I am not sure what the problem is, and I am looking into it. You can still try to Create your Threads and Upload your Photos, but it is hanging up during the Upload.