1. Log into your cpanel account.
2. In the "Security" section, click on "IP Blocker" Icon.

3. Under "Add an IP or Range" you should enter the IP Address .block.
.. "Add" babies.

Here is Example:
Single IP Address: 192.168.0.1
Range: 192.168.0.1-192.168.0.40
Implied Range: 192.168.0.1-40
CIDR Format: 192.168.0.1/32
Implies 10.*.*.* -- 192.