Keep your free theme “free” by using a child theme. It’s really simple.
What you’ll need:
WordPress installed on your site
A free theme – tonight I’m using Twenty Thirteen
Text editor – a great one is SublimeText
FTP program – Filezilla for PC/Mac, or Cyberduck for Mac (open to suggestions)
First, we’ll break a default theme on a site. Then, update it. This is what you don’t want to have happen to you.
Install your theme either in the WordPress Dashboard or by FTP
Activate the theme
Creating a Child Theme:
Create a new folder for your theme anywhere you’ll remember.
Using a text editor, create a new file and name it style.css.
Inside the style.css file, you’ll add:
Theme Name: Your Child Theme
Save the file. Depending on how you would like to add your theme, create a zip with the folder in it, or add the entire folder to your theme directory by FTP.
Your theme should now be available in the Dashboard to activate it.
One more step if you want to keep the styles of your parent theme:
@import url("../twentythirteen/style.css"); </code>
That’s just the beginning. Need to make a change to the page template? Copy the template into your child theme directory, make changes, save it and add it to your site.