Moving Spawned enemys


I have a little problem and hope u guys can help me.
I created with the help of the tween app and enemy that can moves toward the player. But in the game I want to spawn different enemys so there can be a big or endless stream of enemys.
Now the problem is that I have no idea how I can make a refference to the spawned enemy’s :s
It worked with the enemy that alreadt is in the field (see picture) but didnt get further.
Do somebody know how to fix that? Or am I searching in the wrong way?

Thanks in advance and sorry for my bad english.