Mayji! I sent you a private message the other day to teach you how. But anyway, since Matinee is also asking, what you do is
1. Go to the webpage of the picture you want to paste here.
2. Right click the picture and get the URL or the address of the picture. In google chrome it's "copy image address"
3. Go to the page in the forums where you want to post the picture, like for example, here, you go to "Reply to this topic"
4. click the green box icon in the editing toolbar It's right beside the unlink button and the code button (the one that looks like this <>) you need to click the one on the left of <>, the green box
5. a pop up would appear that says "image properties" - below URL, right click and select "paste" so you can paste the link you copied earlier in step number 2. The end of the url should be jpg, bmp or png
6. if you did it correctly, the image should appear in the message box.
7. Don't forget to credit where you got the image from (tell us the source - usually the person who took the picture leaves a name on the picture), the admin is very strict about that since it's bad to use other's pictures without their permission, at least you get to tell us who took the picture so they will get credit for it.
I hope that helps
Oh by the way, there was a big discussion before in the forums if "hotlinking" is allowed - i think that's the method I just gave you earlier, in step 1 - step 7. Usually what the admin wants is that you host the picture yourself so we won't get the bandwidth of the original person who posted the picture. but I think that issue was resolved already when they said that we are allowed to use links from facebook or instagram since they have big servers anyway so borrowing their bandwidth won't be an issue. But if you can, it is better to host the picture yourself in your own website then share the image here. Sorry, it's a bit complicated, even I don't know how to explain it in simpler terms.
With videos, you just cut and paste the youtube link (for the desktop version) and then the video gets embedded automatically.
Thank you very much for all the updates! Yay!