I am having trouble uploading images and after contacting my web host, they said that i should do the following: 

Please update the following script in this location: wp-content/themes/mycustomtheme/functions.php 

 add_filter( 'wp_image_editors', 'change_graphic_lib' ); function change_graphic_lib($array) {\ return array( 'WP_Image_Editor_GD', 'WP_Image_Editor_Imagick' );\ }

(mycustomtheme is the current using theme)

Can you help me with the location? Because when I replace "mycustomtheme" with "soledad", i get this message on the page: "Fatal error: Call to undefined function add_action() in /home2/christianna/public_html/wp-content/themes/soledad/functions.php on line 20"