Having trouble starting building my own rom.

[drebbe]

I'm having troubles trying to build my own rom and understanding a few things.

1. I have BuildOS installed
2. I've downloaded WM6.5 21501 from the updater
3. I only have AT&T as an option in the carrier drop down (I need sprint)
4. I've downloaded Calkulin's 21815 kitchen and would like to use that inside BuildOS, or any kitchen that i've tried downloading.
5. Whats the difference between kitchen and sys?
6. Is there a clean generic kitchen with just 21815 and no modifications (where do the people making these kitchens get the version update)?

Here is a list of C:\Program Files\PPCkitchen.org\BuildOS\Kitchens:

07/01/2009  04:48 AM    <DIR>          .
07/01/2009  04:48 AM    <DIR>          ..
07/01/2009  04:00 AM        22,568,946 000_Shareware.rar
07/01/2009  04:01 AM         3,493,824 PPCKitchen_Addition.rar
07/01/2009  03:57 AM       165,914,919 PPCkitchen_OEM.rar
07/01/2009  04:00 AM       181,867,656 PPCkitchen_OEM_VGA.rar
07/01/2009  04:31 AM        37,504,627 Raphael_Core.rar
07/01/2009  04:31 AM                77 readme.Raphael_6.1.txt
01/05/2009  03:58 AM         6,365,572 SYS_20753_192DPI_0409.rar
01/05/2009  03:57 AM        21,084,303 SYS_20755_Common.rar
01/04/2009  10:48 PM         5,379,803 SYS_20757_192DPI_0409.rar
01/05/2009  03:57 AM        20,946,745 SYS_20924_Common.rar
01/04/2009  10:48 PM        22,987,567 SYS_20931_Common.rar
07/01/2009  04:01 AM         7,894,672 SYS_21210_192DPI_0409.rar
07/01/2009  04:01 AM        25,688,204 SYS_21501_Common.rar