I seen they had a 9 pin d-sub to 2x5 com port. I'm trying to make my own cable. Just wanted to know if I can use any port on the mobo cause the 1394 and usb ports all have the 10 pin header with 9 points.
If you check your manual, you'll find that connecting a non-1394 connector to that header can cause serious damage to the board - they usually specifically cite connecting a USB to the 1394. Some of the PCI cards are pretty cheap, cheaper than trying to wire an RS-232 connector to USB.
I'm trying to put a 9 pin d-sub serial connection on a pc without one. Where do I connect it? I have usb 1 and usb 2 headers and 1 1394 header. Am I able to connect to any of these?
No. The headers look similar but they are NOT compatible. The easiest thing to do would be to get a USB-to-serial dongle adapter, but that entails the OS/drivers being aware that there is a USB-to-serial adapter and looking for the attached device on a USB port instead of a COM or tty port. The best solution would be to get a PCI or PCI Express add-in serial port card, which does show up as a "native" serial port to the OS, programs, and drivers. However, that eats up an expansion slot in your computer and these can be more expensive than a USB serial adapter.