There may be other ways to do this but this is how I did it with success.
- go to a picture hosting website such as Photobucket
- upload your image or video to the said photo hosting site
- after loading your material, you should be able to click on a link (IMG CODE) to that particular image/video which you uploaded
- copy that link directly and paste it into the body of your message here
*replace the ( ) with [ ]
That will put your image onto this site.