My belly button is gone red and used to give out a small bit of green puss when I cleaned it bu now it doesn't bu is still red and gives out a tiny amount of gew once a day.
The person who pierced my belly button said to put sat in hot water from the kettle and wait for it to cool and clean it with a cotton bud Is this the right way?

The discharge should be either be white or yellow, which indicates a healthy healing piercing. That is not pus, but is discharge, that goo is your body's way of cleansing the piercing. The warm water, add a it of salt to it to make a 25% salt solution and use this to clean it twice a day. Also, hold a warm compress on the piercing three times a day. Wear loose fitting clothes to allow the piercing to breathe. The site may be red and irritated for a few weeks as it heals, remember this is a wound