SNAP TO OBJECTS
With the snap tool highlighted, put your pointer in an object, and you will see dots around it. Those dots show you which points on the object can be snapped to. On the object you wish to move, place your pointer inside one of it’s dots, click and hold, then move the point to a dot on the other object you’d like to snap to. Those two points will now be at the exact same position.
SNAP TOOL SETTINGS precedes this tutorial
Seen above are the snap points on the surfaces of an object.