while searching for reference calls or freebsd api... don't know how and what to call it.

it seems they are listed in /usr/src/sys/kern/syscalls.master

but, is there complete reference for all these calls, (like the MSDN style) available for programmer??

i couldn't find any of such reference.

In your syscalls.master, the column at the left contains the syscall numbers (that go into eax). Then, you push every parameter in the column at the right, from the right to the left.
Don't forget to clean the stack upon return.
In general, return values go into eax and the CF is cleared upon success and set upon failure.

Other than that, why don't you check your manual (section 2 for system calls)?
e.g. kill: http://www.freebsd.org/cgi/man.cgi?query=kill&apropos=0&sektion=2&manpath=FreeBSD+7.1-RELEASE&format=html

Generally, there are developer documents for the various BSD derivatives. FreeBSD has a developers handbook in addition to numerous other documents. Specific BSD forums exist for users with mailing lists usually serving developers, but could be utilized interchangeably in order to find relevant data on the platform you wish to develop in. There are also C and C++ forums as well as O.S. specialty sites that may provide guidance and/or direction to other more pertinent resources. First and foremost click on ManOfSteel's link above then select the appropriate O.S. version and read on. Man pages are API documentation, but without all of the pretty frames on the top and left sides for headings and navigation.