Once you start a new topic, click the photo icon in the top menu.
You will get a new window that opens, If you want to Upload an image from your phone or computer select click "Choose File"., if you have a link to your image then click on the URL link.
Locate the picture you want to share and click Open. Then use the menu on the right to select the Format, position and size of your image to adjust how you'd like your picture to appear and then click "Done."
You should now see your picture in your message. You can edit the settings by licking the pencil icon in the top right of the image, or you can drag the image to resize it.