Hello Rob, welcome to the Stovebolt.
To post pics, you first have to set up an account with a picture hosting website like Webshots, Flickr, or one of many others. Most offer a free account with certain limitations, and have an upgrade available for about a buck or two a month. I have had my free account through Flickr for a couple years now, and it hasn't cost me a dime.
You can learn more about posting pictures HERE
You have joined the best site on the web for old GM trucks. We are all looking forward to hearing about and seeing pictures of your projects.