There is no need to learn SSH to secure the server you can also manage your server from your WHM
To secure the server from WHM follow the following steps.
1) Login into WHM >> Server Setup>> Tweak Settings
Check the following items:
Under the Domains section
Prevent users from parking/adding on common internet domains. (ie hotmail.com, aol.com)
Under the Mail section
Attempt to prevent pop3 connection floods
Default catch-all/default address behavior for new accounts - fail
2) Go to Account Functions >> Manage Shell Access
Disable Shell Access for all users
3) Go to Mysql >> Mysql Root Password
Change root password for Mysql
4) Go to Security and run Quick Security Scan and Scan for Trojan Horses often.
5) Go to Server Setup >> Manage Wheel Group Users
Remove all users except for root and your main account from the wheel group.
While you are setting new reseller account privilege from WHM >> Resellers >> Reseller Center always disable the following options
A) Disable "Allow Creation of Packages with Shell Access"
B) Enable "Prevent Accounts from being created with shell access"
6)Go to Service Configuration =>> FTP Configuration
Disable Anonymous FTP