Summarize the following:
Remove the label. Place the unopened can on its side on the bottom of the slow cooker. Fill the slow cooker with enough water to fully immerse the can and cover it with an extra two inches (five cm) of water. For a lighter dulce de leche, cook for eight hours; for a thicker and darker sauce, heat for ten hours. Use tongs or a slotted spoon. Allow the can to cool on a wire rack to room temperature before opening.

Summary:
Prepare the can. Heat on low for eight to 10 hours. Turn off the slow cooker and remove the can.