The putting green should fit with in the sub base area you have made for it. You will want the edges of the putting green to come to the edges of your sub base or come to the edge your existing grass. You may need to remove some sub base to achieve this. This can be done with a shovel. Make certain there are no creases in the turf or it will effect the roll of the ball. If there are very small creases or bubbles then don’t worry about them. When you infill the putting green the small creases and bubbles will go away due to the weight of the infill.