Pick the types of light bulbs you want to mix, and make sure the light fixture can handle it. Most fixtures have a wattage allowance label on them that states what kind of light bulbs they can handle. Check this allowance to be sure your light bulbs don't go over it. The allowance label should be near the light socket.
Remove the old light bulbs from the sockets.
Place the new light bulbs into the sockets. Alternate the different bulbs if you want an even light in the room.