Sheila's just gone out - husband Brian here.
We've looked at this, and the furthest we can get with uploading images is that the facility will be 'available soon' - also, there aren't the text tools here that are shown on the illustration.
Is it possible that this facility isn't available in all areas?
We've explored the possibility of HTML v Plain Text, but there doesn't seem to be a mechanism for toggling between the two. Hope we're not missing the obvious, but it does seem that quite a number of people are having the same problem.