At present, it is not possible to convert your 35mm film single-lens reflex (SLR) camera to a digital SLR. Medium-format cameras that use film backs that attach to the rear of the camera body are well suited for switching between film and digital, and there are digital backs that you can purchase for medium-format cameras--but they are expensive, ranging anywhere from £4,550 up to £9,750 depending on the manufacturer and the resolution the photographer wants to use. It is possible, however, to have the film you shoot with your 35mm SLR film camera converted to digital files.
Load a roll of colour, black and white or slide film into your camera and take pictures as you normally would. Since this is first roll of film you will be converting to digital images, it may be helpful later in the process if you record the exposure values (shutter speed and aperture) for each image. Use this information to see how the scanned file compares to the negative, and for future rolls of film, whether you should expose normally or with a slight over or under exposure.
Have the roll of film commercially processed and choose to have a photo CD made as part of the processing. Ask the retailer how they scan the images and the resolution at which they scan them. Ideally, you would like to have as large of a file as possible and saved in a .tiff format. Saving in .jpeg will result in some information loss.
Once home, turn on your computer, insert the CD into your drive and copy the images from the CD to your computer's drive. Save the scanned files to folder that will be used to save the original digital files. Any editing you do on these files can later be saved to subsequent folder as a .jpeg.