How to Set a Post Thumbnail in WordPress

1. Log on to your Web server via FTP.
2. Go to the folder where your WordPress theme is located and copy over the 'functions.php' file to your computer.

3. Open the 'functions.php' file in Notepad.
4. Add the following code:if ( function_exists( 'add_theme_support' ) ) {add_theme_support( 'post-thumbnails' );}Save the file.
5. Upload the new 'functions.php' back to your Web server.