Importing and including class and functions

Hey guys, am new to flash and am trying to create simple program, I kinda know how to code the program but its really difficult to interpret everything into action script.

For example I created class file in file

class node {
    var x:Number;
    var y:Number;
    var parx:Number;
    var pary:Number;
    var G:Number;
    var H:Number;
    var F:Number;

     function node() {

and few other functions that i want to use in main function in file

now every time i try to import class or include functions in main .fla file >>>

import node;
include "";

its giving me errors >

5007: An ActionScript file must have at least one externally visible definition.

So the question is how do I import class and functions so I dont need to write everything into one .fla file?
Thanks for any help.

ill attach incomplete code to this post.