I'm really new to all of this. I only have a background in Development for C# and a bunch of Microsoft stuff. Nothing really Linux related. So tread lightly =)

Getting Started
I downloaded 64 bit Ubuntu 11.04 iso and created a Virtual Machine in VMWare Workstation. VMWare Player will suffice.

Initializing a Build Environment 
http://source.android.com/source/initializing.html
Complete the sections for Installing the JDK and Installing required packages.

Downloading the Source
$ cd /home/<USER>/
$ mkdir /Android/
$ cd /home/<USER>/Android/
$ mkdir /CyanogenMod/
$ cd /home/<USER>/Android/CyanogenMod/
$ chmod a+x /home/<USER>/Android/CyanogenMod/
$ mkdir ~/bin
$ PATH=~/bin:$PATH
$ curl http://android.git.kernel.org/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
$ repo init -u git://github.com/CyanogenMod/android.git -b gingerbread
The repo init will prompt you for your name and email address.
$ repo sync
The sync process will take about a half an hour.