via a dibsection, how do I load a bitmap in, copy it to a dib section, then read the buffer in a similar way to doing the getpixel method?

I've loaded the bitmap.
I've created a dib section.
I've bitblt'd the bitmap to the dib section.

I try to read the pointer from the createdibsection function call, eg:

invoke CreateDIBSection, bDc, edx, DIB_RGB_COLORS, addr pBb, 0, 0

Same API as used in VB as in C/C++, nothing new here. When I go to read from
pBb, it gives me an error. Maybe because I don't have memory allocated to it.

How do I read the values from the bitmap I copied into the dibsection? I could use GetPixel but I understand that is slow.