You may find at first it makes sailing easier if you set the sheeting so that the boom hauls in no closer than the stern quarter i.e. boom over the rear corner of the deck (see the diagram in the item on sail shape).
If you set the boom to haul in any closer you will begin hauling down on the boom thereby changing sail shape.
We suggest you do this at home or by the lakeside in order to see for yourself exactly what happens.
What you will see, as the boom hauls in towards the centre of the boat is that the boom is pulled downwards towards the deck. Now look at the sail shape and you will see that the mast is now more bent and any twist that was in the sail has now reduced or even disappeared altogether.
If you haul the boom in past the stern quarter when sailing you will find the boat has a tendency to gripe up to wind in the slightest puffs and as a result you will be fighting the wind with the rudder all the time. Sometimes experienced skippers use this characteristic to work their way more effectively to windward but until you know what you are doing we suggest you set the slider as we said at the beginning of this item.