I want to mate a multi-layer piece, but when I try to draw on the underneath layer it isn't visible.
How can I make ALL the white stuff on my main layer turn into nothing (gray/white checkerboard)?

You can simply make the layer above transparent.
On your layers tab, click the arrow by the drop-down that says "Normal" and change it to "Multiply". That makes that layer transparent so anything you do on a layer below it will show through it. Hope that helps!

Suggestions:

1) Manipulate the opacity.
2) Click the 'eye' on the bg layer to make it not visible.

kyupol
Suggestions:

1) Manipulate the opacity.
2) Click the 'eye' on the bg layer to make it not visible.

They eye will just make it reappear once it's saved though, won't it?

Just select the layer in the layer menu and drag the opacity bar to zero. Or just delete that layer altogether.

Nicotine
You can simply make the layer above transparent.
On your layers tab, click the arrow by the drop-down that says "Normal" and change it to "Multiply". That makes that layer transparent so anything you do on a layer below it will show through it. Hope that helps!

When I do that, whatever I draw still effects what I have in the foreground too.

lefarce

kyupol
Suggestions:

1) Manipulate the opacity.
2) Click the 'eye' on the bg layer to make it not visible.

They eye will just make it reappear once it's saved though, won't it?

Just select the layer in the layer menu and drag the opacity bar to zero. Or just delete that layer altogether.

Lefarce is right about Kyupol, but your idea gets the layer completely deleted.

Thank you all, but I'm trying to draw behind a pre-exsiting drawing with a white Bg.



Wait, I figured it out.
used the magic eraser.

transparency is basically deletion, so it should seldom matter.