Chas,
The layout of Flikr has changed slightly since that was done and you now have to search a little more for the 'code' for your image
Jimmy,
hopefully this should help:
On your flickr photostream page >
Left click on the picture of your choice to open it >
Top left of pic are two boxes , left click on "Share this">
Left click on "Grab the HTML/BBCode" >
Left click in the BBCode portal >
Left click on picture size drop down menu and highlight the size required >
Left click on text in the above box to turn it blue, >
Right click and highlight Copy >
Open page where you want to post the picture and then right click and paste directly onto the page , no need for dialogue boxes or anything this way.
Regards
Steve