installing ubuntu on a preexisting hard drive

[mahela007]

My HD is already partitioned into 3 ntfs file systems.
How do I install ubuntu on one these partitions?

[hermes0710]

You can't install ubuntu on ntfs. One of the partitions must be formatted (during the installation) in order to become linux partition. You just boot from the cd and you will be prompted to select in which hd partition you want ubuntu installed.

[mahela007]

which option should I select on the alternate installation cd to format only the selected drive?

[hermes0710]

Format the partition you want ubuntu installed on. I case you need to format other partitions later you may use gparted to do so.