What you need to do is create an account at an online hosting site such as flickr.com, snapfish.com or my personal favorite photobucket.com and upload your images there. Once you've done that, on say photobucket for instance, you can then copy the url for the image (usually displayed between
tags) and them put them in your post. Photobucket usually wraps these tags automatically, or you can type them in yourself.
Between the html tags above would be the url where the file can be found on the internet. So go ahead and get started using this as a guide, if you still have questions or run into problems you can feel free to PM me and I'll see if I can help.