Good Afternoon everyone,
I am having to build a custom partition for my CentOS operating system that i will be putting on an external for class. I have downloaded the live CD for CentOS and am at the screen where i need to start my partitions. I have watched a video giving to me on how to do it but am confused by it. I have formated the external already and when i select sda1 1430796mb ntfs it takes me to the next screen which says add partition. I go down and select the drive and go down to where it says size and put in 100000 for 100gb but when i do that it tells me i don't have enough room. Do i need to use the drop down box labeled mount point and label. The video i watched makes it seem like i have to select the size for the whole drive the do my mount, swap and slash. anyone tell me what i'm doing wrong? Thanks.

The OS needs space to write to you don't have set aside prior to installation. As the disk contains only one NTFS partition (as far as I can gather from your post that doesn't contain 'fdisk -l' nfo) I suggest you use an OS that understands NTFS natively (or use Gparted) to shrink the existing partition and make room for installing Linux. If you use Gparted then you can also create Ext{2,3,4}, format and label partitions prior to installation. Labeling partitions (say "/", "/home" and swap) prior to installation makes the installation easier (less error-prone) as you only have to use the drop-down to pick and assign the right partition.