Help please with wordpress Upgrade!

My entire website has disappeared!

When I go to my ww.wp.xz.cn website (califaces) this is all I see:

Deprecated: Assigning the return value of new by reference is deprecated in /home/p15lh10c/public_html/wordpress/wp-settings.php on line 472

I can’t even log in to do an upgrade. When I try and log in all I see is this:

Warning: Cannot modify header information – headers already sent by (output started at /home/p15lh10c/public_html/wordpress/wp-settings.php:472) in /home/p15lh10c/public_html/wordpress/wp-includes/pluggable.php on line 770

My host site said I need to upgrade my PHP to 5.3.8, but I have absolutely no idea how to do this.

Please can anyone help me out?? I’m lost.
Thank you