WordPress Theme Editing

When modifying a WordPress theme, you can leave the original untouched and make changes to a backed-up copy of its files (called a child theme).

1. To easily identify the child theme you are using, combine the theme name and create a new folder in “wp-content/themes”. (For example, if the original theme is “twentyfifteen”, create a folder named “twentyfifteen-child”.)
2. Copy the original theme’s “style.css” into the child theme folder, then edit “Theme Name” and “Template” as shown below.
   [php]/*
   Theme Name: Twenty Fifteen Child
   Theme URI: https://wordpress.org/themes/twentyfifteen/
   Template: twentyfifteen
   Author: the WordPress team
   Author URI: https://wordpress.org/
   Description: Our 2015 default theme is clean, blog-focused, and designed for clarity. Twenty Fifteen’s simple, straightforward typography is readable on a wide variety of screen sizes, and suitable for multiple languages. We designed it using a mobile-first approach, meaning your content takes center-stage, regardless of whether your visitors arrive by smartphone, tablet, laptop, or desktop computer.
   Version: 1.5
   License: GNU General Public License v2 or later
   License URI: http://www.gnu.org/licenses/gpl-2.0.html
   Tags: black, blue, gray, pink, purple, white, yellow, dark, light, two-columns, left-sidebar, fixed-layout, responsive-layout, accessibility-ready, custom-background, custom-colors, custom-header, custom-menu, editor-style, featured-images, microformats, post-formats, rtl-language-support, sticky-post, threaded-comments, translation-ready
   Text Domain: twentyfifteenTemplate: twntyfifteen
   This theme, like WordPress, is licensed under the GPL.
   Use it to make something cool, have fun, and share what you’ve learned with others.
   */
   [/php]
3. Create a “functions.php” file in the child theme folder with the following source code.
   [php]
   <?php
   add_action( ‘wp_enqueue_scripts’, ‘theme_enqueue_styles’ );
   function theme_enqueue_styles() {
   wp_enqueue_style( ‘parent-style’, get_template_directory_uri() . ‘/style.css’ );
   }
   ?>
   [/php]
4. Copy the original theme’s “screenshot.png” into the child theme folder.
5. Copy the files from the original theme that you want to modify into the child theme folder, then edit and use them.

(Reference: http://codex.wordpress.org/Child_Themes)