Assets/NewBehaviourScript.js(10,29): BCE0044: expecting :, found ';'. HELP!

function Update ()

{

"if:(Input:GetButtonDown(Jump))"; {

"Transform:position:z : 1.0";

}

}

WHATS WRONG WITH THIS? THANKS :D

Your syntax is all off...a typical update function would look like this (in javascript):

function Update(){
    if (Input.GetButton("Jump")){
        transform.position.z = 1.0;
    }
}

I'd recommend heading over to the scripting guide to take a look at how you should be writing your functions.

Get all of those quotes out of there!