Short Answer? See the FAQ thingy at top of this page? Click on that and there are detailed instructions as to how to attach a picture to your post. Print them out and have them handy while you give it a try.
The picture needs to be on a server somewhere on the web that will allow you to "deep link" to it.
If you don't have something already setup and only want to have a couple of pictures available, you can email them to me and I'll put them on my server.
If you are planning to have a lot of pictures you will need an account with a hosting company. I like Club Photo for this purpose. If you pay the fee they will allow you to "deep link" to your pictures. It's really pretty reasonable too.
I am new to this too but the FAQ does explain the process very well. Here's a picture I took yesterday at my first show with this car. No awards for me but lots of awesome cars and car nuts. I even got my entry fee back in a raffle.