Notes on the use of apertures and shutter speeds:
The choice of shutter speed and aperture used when taking photographs will effect the picture you take. Both controls are used to obtain correct exposure on the film but they also have an effect on the 'quality' of the photograph taken.
It is important to understand the differences between the effect on the picture of changing the shutter speed on the aperture to gain correct exposure.

Shutter speed:
A fast shutter speed ( e.g. 1/500th second) will let a small amount of light onto the film; a slower shutter speed (e.g. 1/60th second) will let a lot of light onto the film. It therefore follows that you can use a fast shutter speed when you either have a fast film or are working in bright light, or both. A slow shutter speed will usually be required if you are working in low lighting conditions or are using a very slow film, or both.
There are practical considerations that determine the shutter speed used. If the camera is being 'hand held' then there is a range of shutter speeds that are 'usable' and others which are 'unusable' because it is not possible to hold a camera steady for longer than a certain time. Sharp pictures can usually be obtained holding a camera with a standard lens for no longer than 1/60th of a second.
On a camera with a normal range of shutter speeds this means that using speeds below 1/60th will be likely to give camera shake.
If the subject you are photographing is moving then this can also be a factor and the faster the movement of your subject the more risk there is of blurring. High speed action (e.g. sports etc.) might require shutter speeds of 1/500th or 1/1000th of a second.

Apertures:
The aperture is the size of the hole through the lens. The bigger the whole the more light reaches the film. A large aperture (small number e.g. F1.8, F 2.0) lets in a lot of light and a small aperture (bigger numbers e.g. F16, F22) lets in less light.
Therefore you might need to use a large aperture (e.g. F2.0) in low lighting or with a slow film and a small aperture (e.g. F16) in bright lighting conditions.

Depth of Field:
Apertures also effect the depth of field.
Depth of field in the area in front and beyond the point of focus. A large aperture when the lens is wide open (F1.8 / F2.0) gives very little depth of field and only the distance focused on will be in focus; a small aperture with the lens stopped down (F16 / F22) increases the area in front and beyond the point of focus that will also effectively be in focus.
Lighting situations will determine the control that is available to you in setting the shutter speed and aperture. In low light you may be forced to have a shutter speed as low as practical (1/60th second) and the lens wide open at F1.8 / F2.0. In bright light it may be that you the only options are to have a fast shutter speed ( 1/500th second) and the lens stopped down (F16 / F22) .