Customer perks allow you to take a screenshot or snippet then ctrl+v into the post to auto upload to imgur then embed. You can find info on that here
https://forums.d2jsp.org/topic.php?t=74114203 and the customer upload guide here
https://forums.d2jsp.org/topic.php?t=83903674As for manually doing it you can follow these steps:
1. Open a web page to Imgur.com/upload
2. Take your screenshot/snippet
3. Switch to imgur window and ctrl+v into it
4. After upload right click picture and click "Copy image address"
5. Put between BBCode brackets like the below
Code
[IMG]ImageURL.jpg[/IMG]
The image must end in .jpg .png or .gif to embed properly. If you somehow end up with an imgur link that has "/a/" in it that's not going to embed as it's the album link. Do step 4 above if you end up with that link.