Either use the .tga file:
1. Go to
http://imgur.com/.
2. Click on "upload images". (It is a blue button with a upload-to-cloud icon on it, located at the top left of the screen.)
3. Click on "browse your computer" and select the .tga file.
4. Wait until the image is uploaded.
5. Right-Click on the image and select "Copy picture-url".
6. Use [ IMG ]<ctrl-v>[ /IMG ] to put the image in your post.