Short answer; It's not!
Any graphic or sound file you want to include in a post on a web site has to be stored on a server on the web. It can be your server or someone else's, but it's got to be on the web, not your hard drive.
FreeRepublic does not provide space for anyone to store images, so you'll have to find your own.
There are a few sites that allow you to sign up for a free account to store your pictures. They usually don't allow you to link to your pictures from other sites, so this isn't going to help you.
Many ISP's provide you with a certain amount of storage space, this might be your best bet. Contact yours and find out.
Good luck!