On the top panel, toward the right, you should have a speaker icon. When you
click on it, one of the options might be "Sound Preferences."

I *think* nVidia MCP61 describes a motherboard, and your sound adapter is
probably a Realtek ALC888. If you open Accessories/Terminal and enter the
command: lspci
it will list many of your devices, and one of them is probably your sound
adapter.