To add an image to a post:1. Create the image by taking a screenshot with the PrtScn button and paste the image into an application such as Paint. Save the image. Alternatively, you can use another application such as Windows Snip to create the image.
2. Crop the image to show what you want to display and possibly add markings to highlight certain areas. You can use Paint for this.
3. Upload the image to an image hosting site such as
MediaFire or
ImageShack. These are both free image hosting sites.
4. Get the direct link to the image and copy it. This link cannot be a page which has the image on it, but must be the actual address of the page. It should end in .jpg, .bmp, or .png if it is the address of the image, such as
http://www.example.com/screenshot.jpg.
5. In the post that you want to add the image to, you can simply paste the link and post it. Example:
http://upload.wikimedia.org/wikipedia/en/b/bd/Windows_7.png(Advanced) To make the image actually appear in the post.6. Surround the direct link with the tags
to make the actual image appear. It should look like:
[img]http://www.example.com/screenshot.jpg[/img]
Example:

7. You can make the image link somewhere by adding the
[url=http://www.example.com/link]
tags. So the full link would look like
[url=http://www.example.com/link][img]http://www.example.com/screenshot.jpg[/img][/url]
Example:

8. Now, you can center your image by adding the
tags around the link.
Example:
9. Finally, you can resize the image so it doesn't take up the whole page by adding 'width=' or 'height=' in the img tag, so it would look like
[center][url=http://www.example.com/link][img width=200]http://www.example.com/screenshot.jpg[/img][/url][/center]
Example:
So, as you can see, it can get complicated. But of course, the final steps are not entirely necessary.
For additional tags, please see
this page. I am not sure if they are all implemented here.