Ooh, lucky you! I saw some pics you posted last month (nicely done!), but nothing from that movie.
As for posting images, it's not all that hard. Look above the "Enter Message" box when posting/replying, and click the "bb code" link. The [ img ] [ /img ] tags are what you want for linking to an image, and the [ url ] [ /url ] tags for linking to, say, a Flickr page or Tumblr post where the image came from.
(Also, basic HTML works too -- the < img > < /img > and < a href= > < /a > tags are what you want.)
Or if that's too complicated, just paste the address in as text (https://www.example.com/example-image.jpg) and we can paste it into another tab. (I'll probably reply with a link post of my own if you do that. :-) )