Ok I think you mean this...
you at the green and u see left to right break and aim marger at the hole. and you are asking how do you aim?
well, it's a complex question but i'll try to simplify:
you want to aim left to negate the break. how much you aim will depend on the break and your estimation of it. that's where practice comes into play.
also, elevation and speed of putt comes into play....but best advice is, hit it and see the result and adjust next time. you may keep physical or mental notes. but experience is key
some of us have 4000+ rounds and are still learning
-wgticon