An explanation of your digital camera's manual mode really requires a two-pronged approach. The "manual mode" proper is often accessed by rotating the function dial to the "M" position, or choosing a menu setting. What manual mode does is it allows you to dial in your own settings for aperture and shutter speed, thus controlling the depth of field and exposure compensation (brightness vs. darkness) of your photos. The second facet of manual shooting involves focus. Instead of pushing the shutter button down halfway and letting the camera focus the scene, you adjust the lens accordingly, creating your own focus.
To begin, I'll discuss the manual mode, or "M" setting first. To comprehend this mode, you need a rudimentary understanding of what aperture and shutter are and how they work in tandem to create photos. Explaining all the fine points of aperture and shutter could fill a book, which is why I recommend you visit your local library and check out a simple digital photography book.
Ok, back on trackaperture is like a valve on a pipeline: it can be adjusted to either let more light in or let less in. A wider aperture will allow more light in and also yield a softer depth of field (DOF). On the other hand, a more constricted aperture will allow in less light, but will yield a sharper DOF. Aperture is expressed in numbers called f-stops. To really complicate the matter: a smaller f-stop number actually means a wider-open aperture, whereas a larger f-stop number equals a smaller aperture opening. Confusing for sureagain, I suggest that book
Shutter can be thought of as the curtain on the stage: it opens and closes to control when light enters the camera through the aperture. A wider aperture, allowing in more light, generally allows for a faster shutter. Remember though, that wide aperture will yield soft DOF. A pinhole aperture will give you razor-sharp DOF, but a longer shutter will be necessary to gather sufficient light.
Now that you're probably scratching your head regarding aperture and shutter, you can begin to apply these principles in manual mode. Reading a good digital photography book will explain more about the situations that can call for a specific aperture and/or shutter speed combination in order to yield interesting results. An example: a subject that is backlit by a window. If you let the camera expose, it'll dial in a tighter aperture and quicker shutter to compensate for the light coming in through the window, leaving the subject as a silhouette. In this case, manually setting up a wider aperture and slower shutter may blow the highlights to kingdom come, but will give the subject a flattering glow.
Manual mode is often accessed by rotating the dial to the "M" icon or through a series of menus and/or buttons. Consult your user's guide to find out exactly how your specific model works. Additionally, you can try the "A" (aperture priority) or "S" (shutter priority) modes, if available. These let you set the respective part manually, and then the camera syncs the other one to work in tandem. It's not a fully manual mode, but observing the camera's settings may help you learn how to blend shutter speed and aperture.
The other facet to manual shooting: focus. Most digital cameras have advanced auto-focusing systems that do a fine job. However, there are times when the auto focus just isn't seeing things your way. Or perhaps you want to get creative and do something such as intentionally place the subject out of focus. This is where manually focusing your lens comes in handy. The process is pretty simple on most digital point-and-shoots: manual focus is either accessed via a menu setting and/or a button. Consult the user guide to find out. Once in manual mode, focus is toggled by buttons; a joystick; or on some advanced models, a lens-mounted focus ring. On digital SLRs, manual focus is often the default mode, and is always adjusted directly on the lens via focus ring.
Taking your camera off "auto pilot" and doing some of the legwork can be a bit intimidating at first. Like I said before, a good digital photography book will explain all that you need to know if you're a little unsure of yourself. Or just simply experiment with your camera-it is digital-there's no film processing costs! Aperture, shutter, focus-these aren't nearly as hard to learn to adjust manually as it may seem, I promise! After all, I managed to teach myself these concepts, and have gone on to become a serious amateur photographer, even getting paid for some of my work!