Also, the matter of the disk, as it falls into the black hole, transfers its angular momentum to the hole, which also helps to align the hole's equator with the accretion disk.

LLDIAZ: As for mass: Think of a lead bar that weighs 100 pounds. Then think of a pile of feathers that weighs 100 pounds. They both weigh the same, but the feather pile is much bigger. Same thing with a black hole. Black holes have a lot of mass in a small size.

Check out this article LLDIAZ, it may answer some of your questions:

http://en.wikipedia.org/wiki/Density

Size and mass are different quantities, but the difference can be intuitively confusing, as we tend to naturally use the size of an object as an indicator of it's mass quite naturally here on Earth.

Size is the physical extent of an object. You can describe it with more specific terms such as width, height, thickness, volume etc. Size is a bit of a general term.

Mass is the measure of how much matter an object contains. Intuitively, a heavier object contains more mass that a lighter object, etc. It is measured in Kilograms in the metric system.

The two quantities are related by density. A large object containing not much mass is regarded as relatively less dense (such as a balloon filled with air) than an object that is smaller and contains more mass (such as a block of lead).

And so we come to black holes – these are the densest objects in the universe, containing many stars worth of material crammed into a very small space by a phenomenon known as gravitational collapse. Check out this article if you feel like reading further:

http://en.wikipedia.org/wiki/Black_hole