Kickstart files are plain text files, you can create them using a text editor or the graphical utility system-config-kickstart or even by copying the file from an already installed machine. When you install a machine a record of your installation options is kept in the file anaconda-ks.cfg in root's home directory.
system-config-kickstart offers a nice graphical utility and is a good starting point for your first kickstart file, but I find that I more often rely on editing the file myself. If you wish to use system-config-kickstart, it is in the package of the same name.
There are 4 sections to a kickstart file:
- commands
- %packages
- %pre
- %post