Pages can have templates, but not posts. You have created a custom page template. There is no out-of-the-box way to have a post template, but there is a highly rated plugin called Custom Post Template that will do what I think you want to do.
Pages can have templates, but not posts. You have created a custom page template. There is no out-of-the-box way to have a post template, but there is a highly rated plugin called Custom Post Template that will do what I think you want to do.