Can’t access WordPress admin login

I need help solving my admin login issue. When I try to go to my admin page, http://madfocusmedia.com/wp-admin, I get this error message.

Deprecated: strpos(): Non-string needles will be interpreted as strings in the future. Use an explicit chr() call to preserve the current behavior in /hermes/bosnaweb15a/b936/d5.millenni/madelbarco/wordpress/wp-content/plugins/booked-calendar-feeds/updates/plugin-update-checker.php on line 833

Warning: Cannot modify header information – headers already sent by (output started at /hermes/bosnaweb15a/b936/d5.millenni/madelbarco/wordpress/wp-content/plugins/booked-calendar-feeds/updates/plugin-update-checker.php:833) in /hermes/bosnaweb15a/b936/d5.millenni/madelbarco/wordpress/wp-includes/pluggable.php on line 1265

Warning: Cannot modify header information – headers already sent by (output started at /hermes/bosnaweb15a/b936/d5.millenni/madelbarco/wordpress/wp-content/plugins/booked-calendar-feeds/updates/plugin-update-checker.php:833) in /hermes/bosnaweb15a/b936/d5.millenni/madelbarco/wordpress/wp-includes/pluggable.php on line 1268

What does this mean? And, how do I fix it?

The page I need help with: [log in to see the link]