Usually means you have to maintain your own website to serve images from another location; geocities doesn't allow "hot linking". The cheapest web service in town I've found is www.your-site.com which comes to $80 a year for hosting and domain name registration. I've had no major problems.
I was able to post mine on here without using a website...i think i did it by just puting in C:\mydocs (insert the rest of the folders here). If you want a site i think geocities and yahoo host sites for free.
Skibum, yahoo and geocities will not allow hotlinking... i.e. serving the pictures outside of their own web addresses. You couldn't use the URL / post image technique on these boards to show pics that are hosted on their systems.