Well it was quite pain (as a newbie) installing Pico on FreeBSD, but heres how to do that quick.

Login to SSH as root.

Sometimes, direct root login is disabled. Do this then,

# su -
# password: [Enter your WHM root pass]
# [Hostname]: [Ready to work ]

To Download ports:
# /stand/sysinstall
- Go to Configure (post install)
- Go to Distributions
- Select 'ports'
- Select 'ok'
From there select FTP transfer (ftp.freebsd.org is ok) and it should download the ports into /usr/ports. When it's done, just exist sysinstall and run the commands I stated earlier.

It'll take a while to download.

after its finished downloading, do this:

# cd /usr/ports/editors/pico
# make install

and it'd install it for you.

DONE!!

For security reason, FreeBSD only allows su to root user,
if user is member of wheel group. Wheel group is a special group for administration purpose. Add your normal user to this group using pw command using following:
# pw user mod username -G wheel

So to add user amir to group wheel run command as follows:
# pw user mod amir -G wheel
# groups amir

amir wheel

Now su will work for amir.

You can disable this behavior complete for all users (not recommended until and unless you trust ALL of users):
1) Open pam configuration file for su using text editor:
# vi /etc/pam.d/su

2) Look for following line and comment it out:
Line:
auth requisite pam_wheel.so no_warn auth_as_self noroot_ok exempt_if_empty
Replace with:
#auth requisite pam_wheel.so no_warn auth_as_self noroot_ok exempt_if_empty

3) Now all users can use su command.