If you have created your own WordPress theme and want to add a name, version number, etc to identify your theme, then all you need to do is is add a small bit of code to the top of your style.css file.
Theme Name: Treesme
Author URI: treesme.com
Description: This theme is for my sites…
Example code (minified style.css version):
If you use a compiler to create your style.css file, the ‘Theme Details’ will get erased each time you compile your styles.css file. You will have to re-enter the ‘Theme Details’ code at the top of your style.css file when you have finished compiling.
Save the updated style.css file and compare the difference: