Forum Moderators: not2easy
What action do I need to take to comply with that license and Secondly, will this affect the copyright that I hold for the rest of the content of the webpage?
If it's their picture, they may grant you a license, but you will not 'own' the picture, or be able to pass it to others, unless they, too, follow the terms of the license.
Also be careful; some WikiP images are NOT theirs, and you will need to go to the source to get a license to use it.
If I include this image in my webpage, does that mean that my webpage must also fall under the conditions of the GFDL and therefore be freely copyable?