Can somebody please help?

I built a site:
http://www.dynamo-led-displays.co.uk
with dreamweaver but sometimes when people log on to site they get the following error.

Fetching of original content failed
due to Proxy Publisher Failure <Error Name>. If you own this
domain, please consult this FAQ.

I have read I need to implement the X-Forwarded-For header

but have no idea how to do this?