Since there are still a lot of people who don't know how to properly post an image on here, I decided to make a thread with clearer instructions (and I wouldn’t want to go searching through the official forum topics, either). Scroll to the bottom if you want to skip the explanation.

First of all, which button do you press? There's a button above your text box, it looks like this: Pressing this button will automatically give you [img][/img], with your cursor between them. If you click the arrow next to the button, you can align your image where you want it. Here's what it looks like:

Left aligned

Centered

Right aligned

What does this mean? This means it wants you to put in the image's link. That's right, you've gotta put it on the Internet!

But one can't simply do this: See? It doesn't work! Have you ever gone on a search engine looking for pictures? At first, don't you click "View image" instead of "Visit page", because you don't want to see all the stuff around the image, you want to see the image itself? The link of this kind of page is the link you should be putting between [img][/img].

So after that lengthy explanation, here's the simple steps:

Prntscr.com / Lightshot
1) Go to prntscr.com (optional: make an account)
2) Upload the image file.
3) Go to the link.
4) Right-click the image and press "Copy image URL". (iOS: hold down, press "Copy image". I don't know Android or other mobile ways.)
5) On here, press the image button, and paste the link.

Deviant Art:
1) Post your image (on your Deviant Art, duh).
2) Right-click your image on its Deviant Art page. (iOS: hold down, press "Copy image". I don't know Android or other mobile ways.)
3) Press "Copy image URL".
4) On here, press the image button, and paste the link.

Happy posting !!

God damn if this is hugely unnecessary or if I put it in the wrong place.

Guji, I only realised you made this after I finished my forum tutorial. I'm sorry!
I hope you don't mind, but I'm going to link this thread onto my tutorial. You will get full credit of course.

I apologise again.

Lurksindark

Oh it's perfectly fine. In fact, making an entire forum tutorial is probably more helpful!

Thank you! However, mine was nearly as detailed as this. I'm very certain this will help others who don't use a Windows like I do!
(Also I forgot to mention the alignment option on mine. Shoot!)