How to add in maxima my own lisp-function as native?

Greetings to all participant of this mail list.
I'm Russian student and I make some scientific work. Part of this work -
it's to add in Maxima some lisp-functions and make it works. I don't know
lisp excellent, but I know lisp enough for my purposes; I compiled Maxima
from source successfully also. I've added in src/comm.lisp (there were many
source lisp-files - I've just suggested, that "comm" means "common") for
test my own lisp function and called it my_function. This function have been
available now; but user should run it like that:
:lisp (my_function $x);
And result, of course, will be shown in lisp-style.
So, my question is: there are a way to add some function, which was written
at Lisp, in Maxima, but this function must run and show result not in
Lisp-style? Such as like that:
my_function(x);
And how better to extend Maxima by my own functions? I mean, in what file in
src/ should I add my own lisp-functions?
I will be appreciate for any information about my questions; I also will be
glad to get from you any links to documentation and articles, which
dedicated to this. But I better prefer material, where author give real
example of adding lisp-function in Maxima, but without lisp-style call of
this function.

With best regards, Ivan Zorin.

P.S. Sorry for my bad English - it's not my native language, but I hope that
you understand, what I would like to find out.