Show one array element for 1 sec

I’m trying to make a memory like game. It might be called Simon or Simple Simon or something. Basically something is shown for a second and then gone, then the user clicks that something. Then two or three things are shown in order and then gone and the user clicks the order.

I’m stuck at the very beginning, just showing something from an array for half a second or so then stopping and then starting over and adding one more element.

Any ideas?