I wonder what it is that you wish you knew how to do, Alffe. Is it posting pictures? If so, I can give a quick/easy walk through on how-to do so .

First, just make sure the photos are stored somewhere on your computer or are hosting by a web server/site.

When posting a message, scroll down (below) the area where you type the body of text and see the Option entitled: Attach Files. Click on Manage Attachments. A small window (or pop-up) will open and display the options:

Upload File from your Computer
or
Upload File from a URL

The first option is easier, I think, since the second option also means knowing the exact URL or link to type or paste.