2D enemy movement to target

I cant figure out how i would do this. In the game the enemies spawn on the sides out of view of the camera and “walk” to a target in the certain of screen. The point is to stop the from pulling the target off the screen. I just want to know how i would get them to move. I used an instantiate script set so it shoots an enemy out but in order for it to reach the cameras view the gravity needs to be turned off. I tried transform position but i couldnt figure out how to give the object a speed to keep it from instantly moving to that point.

if anyone has any ideas it would really help.

Use Time.deltaTime. For example:

var speed : float = 10;

function Update () {

//move on the z-axis by 10 every second
transform.Translate (0, 0, speed*Time.deltaTime);