Take out the house and whatever else is in the snakes cage (excluding the water bowl) and put the snake in. Put the mouse in with the snake, and cover...
This is an instructable telling you how to feed a corn snake. The same methods work with most colbrids (milksnakes, king snakes, rat snakes, bull snakes.) I will show how to feed pre-killed mice to a snake, as I am not very experienced in feeding live. I feed my corn snake 3 adult mice every 2 weeks.
Step 1: Supplies Needed
You of course need the snake, the mice, and I like to use tongs, because my snake will strike at anything. You also might want a cardboard box to feed your snake in, so the snake doesn't become accustomed to eating in its cage. (so its mindset isnt "Moving-cage-EAT".) Look at the chart below to learn the sizes of mice.