1. First you have to know the BBcode for posting an image. The BBcode is [img*]url[/img]Minus the asterik/star
2. The url must end in the actual image url. Meaning it has to end with .png, .jpg, etc. An example would be [img*]https://i.imgur.com/43ddDwa.jpg[/img]
3. You can find the image URL by either clicking an image directly and checking the address bar or just right click the image and click Copy Image Address.
Sidenote: You can use the web page urls of Imgur and Gyazo but you have to manually input a .png at the end of the URL to make them appear as images on the forum, and imgur posts have their own special link in the picture itself you have to copy.
Examples: [img*]http://imgur.com/8Cowlwt[/img] will not work but [img*]http://imgur.com/8Cowlwt.png[/img] will. Same goes for Gyazo links.
Images can go in posts or your signature but be forewarned, they do have a set size you cannot go over. I know .gif urls can go into the Signature but I'm not sure if gifs will work in a normal post. I'm sure someone else will come along to correct me though.
I hope this helps, and have fun [img]posting.
