The FreeBSD project already have a very thorough and complete set of documentation covering how to install FreeBSD. I know the following section is rough, it's only included since it was requested. I highly recommend reading the fine documentation at http://www.freebsd.org/docs.html.
Burn a copy of the boot CD (http://www.freebsd.org).
Reboot with the CD in your drive, make sure your BIOS is set to boot off of CDROM first.
Sysinstall (the FreeBSD System Installer) will run.
Select "Standard"
FDISK Partition Editor - Slices
d - Delete any existing "slices" (any data will be destroyed).
c - Create a new slice, the defaults will be fine.
s - Set that slice to be bootable.
q - Save the changes and quit.
Boot Manager
Select standard, as long as you don't have any other OS' on that disk. This means the disk will boot straight into FreeBSD.
Disk Label Editor
c - Create partitions
a - Use auto defaults (you are free to enter your own values if you wish)
q - Save the changes and quit.
Choose Distribution
Select Minimal.
Install Method?
FTP
Choosing a local mirror. Since you'll be installing via FTP, a quick connection means everything.
Choose Network Card. The default should be ok.
IP 6 = No
Perform as Gateway = No
Enter your network settings here, you must know your gateway (probably your router) and your DNS server (probably provided by your ISP).
SSH = Yes
Inetd = No
DHCP = No
FTP = No
NFS Server = No
NFS Client = No
System Console = No
Time Zone = Yes
Linux Binary Compatibility = No
Mouse = No
Packages = No
Create User = Yes
Exit Install
Remove CDROM and reboot.
Then you MUST install the port tree.
Login as root, then run sysinstall.
Configure > Distributions > Ports (and perhaps the Man pages)
Go grab a coffee!
Make sure you update the locate database (this is mentioned in the next chapter) once the ports are installed, this will make your life much easier.
You now have a fully functioning FreeBSD server with the latest ports ready to be easily installed. I highly recommend that you make sure you keep your FreeBSD system updated.
Upgrading the System
(coming soon)
Portupgrade
(coming soon)
[I'm still working on the most efficient and easiest way to display this]