Hi bomber,

it's right, you have to write the game for multiplayer, here is just a small example that runs under A7.07 using Lite-C.
Maybe it helps to see concepts.

// Simple Multiplayer
// 3D Gamestudio A7 Version 7.07 commercial

#include <acknex.h>
#include <default.c>

ENTITY* clPlayer;
ENTITY* svPlayer;

var isMove = 0;
var isInput = 0;
var showX = 0;
var showY = 0;

function moveMe () { // movement for both on server
while (1) {
my.x += my.skill1 * time_step;
my.y += my.skill2 * time_step;
ent_sendnow (me);

isMove++; // moveMe() running?
if (isMove > 999) isMove = 0;
wait (1);
}
}

function getInput () { // wsad control on client and server separately
if (connection == 2) me = clPlayer;
if (connection == 3) me = svPlayer;

while (1) {
if (key_w == 1) my.skill1 = 5;
if (key_s == 1) my.skill1 = -5;
if (key_a == 1) my.skill2 = 5;
if (key_d == 1) my.skill2 = -5;
if (!key_any) {
my.skill1 = 0;
my.skill2 = 0;
}

if (connection == 2) send_skill (my.skill1, SEND_VEC|SEND_UNRELIABLE);

showX = my.skill1; // show input
showY = my.skill2; // show input
isInput++; // getInput() running?
if (isInput > 999) isInput = 0;
wait (1);
}
}

////////////////////////////// main ///////////////////////////////////////
function main () {
level_load ("M.wmb"); // just a platform and a cylinder at +X for orientation
wait (-0.5);
vec_set(camera.x,vector(-200, 0 , 20));

while (connection == 0) wait (1);

if (connection == 2) { // client
clPlayer = ent_create ("BlueBox.mdl", vector (70, 30, 0), moveMe);
}

if (connection == 3) { // client / server
svPlayer = ent_create ("RedSphere.mdl", vector (70, -30, 0), moveMe);
}
wait (-0.5);

getInput();
}

PANEL* diag_pan = {
flags = VISIBLE;
digits (4,10,"Diagnostics",*,1,NULL);
digits (4,20,"connection =",*,1,NULL);
digits (80,20,3.0,*,1,connection);
digits (4,50,session_name,*,1,NULL);
digits (4,60,player_name,*,1,NULL);
digits (4,70,"Input :",*,1,NULL);
digits (80,70,3.0,*,1,isInput);
digits (4,80,"Move :",*,1,NULL);
digits (80,80,3.0,*,1,isMove);
digits (4,90,"Inp X :",*,1,NULL);
digits (80,90,3.0,*,1,showX);
digits (4,100,"Inp Y :",*,1,NULL);
digits (80,100,3.0,*,1,showY);
}