Buy some dog shampoo.
Fill the bath/sink up with some water. Not too hot and not too cold. Fill the bath up to a suitable level for your dog.
Put some dog shampoo into the running water.
Lift the dog into the bath/sink.
Rinse the dog with warm water.
Apply dog shampoo onto the dog with a cloth.
Massage the shampoo into the the dogs hair.
rinse off the shampoo with warm water, you can use a shower head or a cup and water.
repeat step 7 & 8
Lift the dog out of the bath/sink using a towel.
Dry the dog off with a towel or hair dryer.
give the dog a treat and tell him/she they are a good dog.