Wordpress has hundreds of themes that can be accessed from your admin interface. Just select a theme to download it and then activate that theme.

Some themes have special features or may even require certain plugins to function. You can always go back to another theme if you have problems when testing a new theme.

Using Child Themes

It is highly recommended if you are editing theme files (for example customising the footer.php text) that you create a "Child Theme". This allows you to protect your changes when the theme is updated.

Adding a Child Theme

Let's take the example of creating a Child Theme for the theme:twentyfifteen

  1. create directory a theme directory called twentyfifteen-child
  2. inside that directory, create style.css
  3. also create functions.php

edit style.css

the file must begin with the following header, notice, the Template name and URI

/*
 Theme Name:   Twenty Fifteen Child
 Theme URI:    http://example.com/twenty-fifteen-child/
 Description:  Twenty Fifteen Child Theme
 Author:       John Doe
 Author URI:   http://example.com
 Template:     twentyfifteen
 Version:      1.0.0
 License:      GNU General Public License v2 or later
 License URI:  http://www.gnu.org/licenses/gpl-2.0.html
 Tags:         light, dark, two-columns, right-sidebar, responsive-layout, accessibility-ready
 Text Domain:  twenty-fifteen-child
*/

NB: the Template line must match the parent theme directory name

edit functions.php

<?php
function my_theme_enqueue_styles() {

    $parent_style = 'parent-style'; // This is 'twentyfifteen-style' for the Twenty Fifteen theme.

    wp_enqueue_style( $parent_style, get_template_directory_uri() . '/style.css' );
    wp_enqueue_style( 'child-style',
        get_stylesheet_directory_uri() . '/style.css',
        array( $parent_style ),
        wp_get_theme()->get('Version')
    );
}
add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_styles' );
?>

NB: This example function will only work if your Parent Theme uses only one main style.css to hold all of the css. If your child theme has more than one .css file (eg. ie.css, style.css, main.css) then you will have to make sure to maintain all of the Parent Theme dependencies.

Other files

Once you have set up the child theme, you can also protect other files.

For instance, if you want a custom footer, just copy the Parent Theme's footer.php file to your Child Theme diretory and edit it. Wordpress will pick files fro, the Child Theme directory in preference to the Parent Theme.

Troubleshooting

White Screen

This usually happens when you've installed an incompatible theme or not updated a theme when Wordpress itself has been updated. The website may appear to show nothing but a white screen. Thankfully, it's usually easy to fix, just log in to the admin interface at http://yoursite.net/wp-admin and update or change the theme.

Permission Issues

Sometimes you may have uploaded files by SFTP and then editing via the web interface may fail because of a permission issue. This is usually because the permissions on your uploaded files may have been marked writable for your user only (whereas the webserver user needs to write for web-based changes). This is easily fixed by marking the files as "group writable".