Create a new file in your WordPress theme folder with a name that reflects the custom post type you want to create a template for, such as single-{posttype}.php.
Add the necessary PHP comments at the top of the file to make it a valid theme file, including the theme name, author, description, and so on.
Use the WordPress loop to display the relevant content from the custom post type within the template file.
You can use template tags and custom HTML/CSS to structure and style the content as needed.
Save the file and ensure it is located in the root directory of your WordPress theme.