1. The pic you wanna post must be available already on the web. e.g some image hosting site or right from the source. Open a new Tab in your browser and navigate to your pic... Once you have found the pic, right click on the pic and choose "View Image"
2. Copy the url address from the pic and go back to the tab with TERB loaded.
3. In the thread you want to post in, click on "Post Reply".