Creating custom post template

Flynn, you told me how to create a custom post and page template. I did make a custom PAGE template, and it worked fine. But it didn't work for the POST template. I did as you said, exactly, but the new template does not show up in the drop-down template box in the new/edit POST area. It does show up in the drop-down template box to the right of the PAGE editing area, but that isn't helpful when doing a POST.

I put this at the top of the new template: And I named it my-garden-template.php and uploaded it to the theme directory. I used the index.php as the base.

What am I doing wrong?