Help with install of PHP 5.2.4

I am totally lost. I am told by WordPress that I need “PHP version 5.2.4” in order to function properly. [See the warning below.] Automatic update doesn’t work, though it has in the past. I have no idea where to get 5.2.4, or what to do with it were I to get it. I write content; I don’t program code. And WordPress Codex is about as opaque as they come. HELPO, any one!

WordPress warning:
“An updated version of WordPress is available.
“You cannot update because WordPress 3.2.1 requires PHP version 5.2.4 or higher. You are running version 4.4.9.
“While your site is being updated, it will be in maintenance mode. As soon as your updates are complete, your site will return to normal.”