Is there a way in Web Host Manager to block entire ranges of IP Addresses? If so how?

Not that I know of but APF will do the trick.

this is a very noob question so forgive me please. What is APF?

Firewall software. Covered here: http://forums.servermatrix.com/viewtopic.php?t=2198

Or
You can use the iptable to block the IP

iptables -A INPUT -s IP_address -j DROP

if you want to block subnet

iptables -A INPUT -s x.x.x.0/24 -j DROP


which will block that ip address, if you reboot the server the iptables rules will be flushed, please make boot script to get rule for the nex reboot.

hope that helps