After uploading your pictures to the Picture Gallery, go to the picture in the gallery and right click on it to get its properties, copy the URL for the picture out of the properties (ctrl + c to copy ctrl + v to paste).
When you are creating a new post or doing a reply you will see under the subject box some buttons. One is the "Img" button. Click that button (or alt + p) then paste the URL to the right of the [img] tag that has been placed into the text box you will be typing into. After pasting the URL click the Img button again. It will look something like this (Except I'm substituting {'s for ['s) so the example doesn't show-up as a link):
{Img}http://www.howtogrowtobacco.com/forums/coppermine/albums/userpics/10006/normal_Tobacco_011.jpg{/Img}
You will not see the picture until you preview your post. If the picture isn't displayed when you preview then make sure you pasted the whole URL. The picture won't display if the URL is wrong.
HTML tags use the / to indicate the end of the statement. The first time you click the Img button the tag will look kinda like this: {img} (Indicating the beginning). The second time you click it will look kinda like this: {/img} (Indicating the end).
Here is the picture displayed by using the above example:
