Wasn't obvious to me how to insert an image in a post when the image was on my PC.

Located Answer

If you have uploaded an image as an attachment, you can click the arrow next to the 'Attachment Icon' and select it from the list. This will be inserted into your post and can be located where you want it displayed.

To include an image that is not uploaded as an attachment and is located on another website, you can do so by copying the full URL to the image, (not the page on which the image is located), and either pressing the 'Insert Image' icon or by typing [img] before the URL and [/img] after it, ensuring that you do not have any spaces before or after the URL of the image. You can insert pictures from your albums (?) in this way too.