http://www.finescale.com/fsm/community/forum/topic.asp?TOPIC_ID=38682
Michael, this link will provide you with the info you need regarding image size etc.
I might be telling you how to suck eggs, but here goes anyway.
To pst an image, firstly you need somewhere on the net to store tham.
Alot of people use this site-
http://photobucket.com/
It's free, and provides you with somewhere to store your in progress pics etc, or anything pic for that matter.
Just create your own account, and there you go.
This is another sight that people use-
http://rongeorge.com/modules/Gallery/
Ron is a great supporter and advocate for Finesacle and the modeling community in general, and has kindly provided this site for others.
For more info, read through this link-
http://www.finescale.com/fsm/community/forum/topic.asp?TOPIC_ID=10017
Really helpful!!!!
Now, for a little more info, there is another modeler who provides a site with a bucket of useful info.
http://www.swannysmodels.com/
Swanny is a bloody good modeler, and all round nice guy.
You can usually see his works in progress in the Aircraft section, and he is always around to answer questions, or provide info of some sort.
Lets face it, if there is something you can't find elsewhere, then ask here, someone can alsways help.