Two ways you can do this and it really comes down to image size and laziness.
1 : From your computer (attached images)Small sized images can be easily posted from your computer. When making a post, click Additional Options..., see Attach and click Choose File. Browse for the small image you want, then Post. It may take some time, but your post will contain an attached image.
2 : From the web (photobucket, imgur, imageshack, tinypic, other sites)
Other images that you want displayed directly where you want in a topic can be added from an external website. You may upload your own images to a site, and then find the direct link or image URL of an image (usually you can right click images on a webpage and click Copy Image URL). Copy this link.
On the forums, insert that URL like this in your post :
[img]http://www.google.com/images/srpr/logo3w.png[/img]
Now submit your post.
Extra - 3 : Resizing Images on the ForumsPage stretches are annoying and can be caused by huge images on a topic.
To resize images to the dimensions you want, add width and height to your tag like this :
[img width=200 height=50]http://www.google.com/images/srpr/logo3w.png[/img]200 represents the amount of pixels of the width of the image size I want and 50 pixels is the height.
