photoshop cs3.

i am making a glossy button by following a 'make a glossy button tutorial on youtube'.

* new layer
* fill black
* draw a red color circle (in tutorial he draws a blue circle)
* new layer
* draw a white color circle over the previous red color circle > overlay.
now when i click overlay on the layer palat for this circle, it goes beneath the black fill and invisible on the screen .
but the tutorial i am following shows this remain on top even after apply overlay. what is the problem