In general, the picture must either be on your computer, or in a web URL. The BCC site allows you to use filtered HTML in a visual (WYSIWYG) editor. The editor has a toolbar to make it easy to very your text, and to insert tables and images:
The image insert button is the first icon in the fourth group of icons in the top row. It looks like a landscape picture.
Put your cursor in your text (in a blank line is best) and click the image insert button. You will be presented with the following pop-up:
Click the browse Server button and yet another pop-up appears:
Click the upload button as shown, and then the Choose File button. Browse for the file on your computer and select it. It is not necessary to check any of the small, medium, large boxes. Hit upload. The picture will then appear selected in the server file system, and then click the "Insert file" button to put it into the Image properties dialog. It is a good idea to fill in the alternative text box (for text-only viewers) and here you can specify other properties of your image. Finally, click "OK" and your image will be entered into the editor.