To create images that appear alongside your text, use the "Inline Img" filetype option. If you are going to use this option, please make sure that the image is small!
Alternatively you can use the "Place Img" option to add images (including large ones) to a posting. If you use this option, you should insert [img1] where you want your attached image to appear. If you have multiple placable images, then use [img2], [img3] and so on to place them. Remember that the images must still be approved before they will replace your [img] tags. You can also chose the alignment of your images by adjusting the tag, e.g. [img1=left] will left-align the image, [img1=center] will centre the image, and [img1=right] will right-align the image.