WP Enqueue Problems

I’m having some conflicts. This is what comes up when I debug –

Notice: wp_enqueue_script was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.) in /home4/jessie21/public_html/wp-includes/functions.php on line 3049

Notice: wp_enqueue_style was called incorrectly. Scripts and styles should not be registered or enqueued until the wp_enqueue_scripts, admin_enqueue_scripts, or login_enqueue_scripts hooks. Please see Debugging in WordPress for more information. (This message was added in version 3.3.) in /home4/jessie21/public_html/wp-includes/functions.php on line 3049

Notice: Undefined index: pagename in /home4/jessie21/public_html/wp-content/plugins/rezgo-online-booking/rezgo.php on line 176

Warning: session_start() [function.session-start]: Cannot send session cache limiter – headers already sent (output started at /home4/jessie21/public_html/wp-includes/functions.php:3049) in /home4/jessie21/public_html/wp-content/themes/Divi/header.php on line 1

I’m not the best at writing code, but I can usually follow the directions I receive. Any help would really be appreciated.