Remove all the bedding from your mattress and launder it. A fresh bed starts with fresh bedding.
Move the mattress to an open area so that you can have access to all sides.
Vacuum the mattress thoroughly, front and back, using your upholstery attachment.
Mix upholstery cleaning solution and water in the bucket, following the manufacturer's directions. Soak the cleaning rag; then wring it out until it is slightly damp. Wipe down the entire mattress, re-wetting and wringing the rag as needed.
Apply extra cleaning solution to any stained areas, using the cleaning rag. Use the cleaning brush to gently rub out the stains. Tough stains may require additional treatments.
Spray the entire mattress with fabric freshener (such as Febreze) if desired. Allow the mattress to dry thoroughly. Using an electric fan can speed the process along.