Right, if your making big tuning differences (for example if your peg slips or something) then use the tuning pegs at the top of the cello, but if its only a little difference then use the little pegs just below the bridge of your cello. If your using the pegs at the top, then you are more likely to break the strings. As far as changing strings is concerned, its very similar to changing strings on the guitar but my best recomendation is get someone like a cell teacher or a friend that plays cello to change them so that you dont do any serious damage to the instrument (i.e. snapping off the bridge/ causeing a crack in the wood etc) good luck xxx