Yeah that won't work, pard. The board works on HTML - Hypertext Markup Language - you need a link. You need to either use the image hosting here on this site or an off site image hosting website that gives you a link.
You can click on the image icon in the menu above the message window...... and it will ask you to upload a picture from your computer. That's the easiest way other than using another image hosting website that will give you a link.