Refer the following the steps:
rm -fv csf.tgz
wget http://www.configserver.com/free/csf.tgz
tar zxf csf.tgz
cd csf
sh install.sh
Disable APF + BFD if you have installed on your Dedicated server.
Follow the step given below to do disable it:
sh disable_apf_bfd.sh
Modify the config files in /etc/csf/ to configure CSF
Note : You can also modify the CSF settings in WHM ,if you have it on you server.
The standard cPanel ports are being opened up by CSF.This is by default.