‘I won’t be a very good Top/Dominant because I don’t want to hurt people’
Most Sadists will at some point be the Top in a scene, due to the nature of Sadism being a doing thing, not a receiving thing. Not all Sadists will identify as, or have any desire to be a Dominant though. On the flip side of that, many Tops and Dominants have no Sadistic inclinations at all.
‘What can I do to be Dominant though if I don’t like causing pain?’
Pain play is a huge part of BDSM … for some people. It is the SM (Sadism and Masochism) part of the acronym. If you are neither a Sadist or a masochist though, you still have all the other letters to play with. Bondage and Discipline and Dominance and submission. None of which need to involve pain.