The easiest way to go about this is to use a modern USB turntable for the task, making sure that the turntable at the heart of this is itself decent and of a consistently good quality to accurately represent whatever record it is going to be asked to convert. Using a USB cable, which will more than likely come with the turntable, all you simply need to do is attach both ends to their respective slots, and then to use a piece of audio software like Audacity, to capture the resulting sounds that come from the turntable during playback, all of which should be fairly straightforward.