From your other posts you said you had all the movieclips on another layer.
Give each item an instance name of Bn where n is a number ie, B1, B2, B3

You have a total of 6 items boxed, in your image so select each item and give it that as its instance name.

Code:
var naming:Array = new Array("square", "circle", "pentagon", "triange");
Place the names of your items, ie the text you want to appear here.

Change holder["B"+i].onRollOver = function () { to
Code:
["B"+i].onRollOver = function () {
Not really much more I can explain, I have written what every bit of code means.
I have also explained what I did in detail.

From the sounds of it your new to actionscript 2.0, it might be worth you learning the basics, if you are still have issues understanding.