Since you've stated that your extended partition has 2 logical data only partitions on it, you could always move that
partition to the left, and then extend it to eat up the 6gb of space. You will then be able to create a 6gb logical
partition.

Steps:

1. In terminal type "sudo apt-get install gparted".


2. Go to the Unity Dash, and search "gparted". Click the Gparted result to run Gparted.


3. Right click on the extended partition, and choose "Resize/Move".


4. Change the "Free space preceding" entry to "0", and click "Resize/Move". [To make the button
   clickable you may need to click into one of the other boxes first, but don't edit them.]


5. Click the checkmark at the top of Gparted, and then click "Apply" in the prompt to apply the changes.


6. When it finishes you can click "Close". Gparted will re-scan your devices, and you should now see the
   free space listed in your extended partition.


7. Right click on the free space, and choose "New".


8. Enter you desired partition paramiters, and click "Add". Click the checkmark, and then click "Apply" to apply the
   changes.


9. Click "close". You now have another partition! :)

Notes:

• Never move partitions that have an OS on them, or are being used by a program that will expect them to be in
  specific place unless you know what you're doing as this can have dire concequences like inability to boot and operating system.




• Always backup your entire hard drive (or at least data on the partitions you're modifying) before engaging in any kind
  of disk management activities, because it only takes one error to change your life forever.

Additional Resources:

• Gparted Manual: http://gparted.org/display-doc.php?name=help-manual




• What disk partitioning is: http://en.wikipedia.org/wiki/Disk_partitioning




• What Are The Risks Of Partitioning Drives: https://superuser.com/questions/402569/what-are-the-risks-of-partitioning-drives




• Disks, Partitions, Partition-tables, and Filesystems: http://paste.ubuntu.com/7682570/