what do he mean to full from crown to toe

She means wants to be full of evil and coldness from the top of her head to the tip of her toes.

From the text:

"Come, you spirits

That tend on mortal thoughts, unsex me here,

And fill me from the crown to the toe top-full

Of direst cruelty."

Lady Macbeth is actually talking to herself or the spirits she believes control her destiny. She's telling the spirits that if they want to urge her on with muderous thoughts, they need to make her more like a man....... they need to fill her with deadly cruelty.