Your attic should be ventilated to maintain a healthy atmosphere. Wet and hot air get accumulated in attic leading a highly conducive environ for mold & mildew growth. Hence, it’s always suggested to arrange for sufficient ventilation across the attic area so that the hot & wet air get to escape leaving the area dry which eliminates any chance of mold growth.
Besides, proper ventilation would also keep the place cool and comfortable during the summer months. The good part is that an effective ventilation would keep the cooling and heating bills on a workable status, keeping the roof safe as well.
You are required to put the vent slot in soffit for the intake & near ridge-line for the exhaust. This way, fresh air would easily fill up the attic space through soffit as the warm air would fly away through ridge line. The soffit could come with continuous or discrete vents.