Ian,
Whereabouts are the pictures stored, ie photobucket? They have to be uploaded to a photo hosting site. You then copy and paste the link between the 2 sets of square brackets (I will use curley brackets to demonstrate):
{img}http://i199.photobucket.com/albums/aa317/DDastardly/Image053.jpg{/img}
Photobucket makes this easier from it's own album view as as you click on the image link from a list of about 5 below the pic you want it automatically adds the square brackets around and copies it so all you have to do is paste into the message board text box. Other site may have similar arrangements.
Hope this is clear and is of assistance.
Al