Please help. I can't do it!

Hi! I am a begginer action scipt user. So I cannot solve some problems sometimes like the example shown below:

I want to have some tiles to appear randomly and (when completed) removed randomly...


I planned to do these steps:

1-Duplicate a box movieclip and arrange the duplicated boxes in an order to build tiles (in my tile.zip file there are 99 boxes created),

2-Set visible value to 0 for each box created,

3-Get random numbers from 1 to 99, set the related box's visible to 1 until all the boxes are done. But of course random shouldn't give the same number twice

4-When all the boxes shown in a tile, they must be removed in the same way.

NOT: I think tiles doesn't have to be apeared after they are created. The duplicate process can be randomly happen..