My elder brother told me that a non muslim has walked from the washroom of my house to the door of exit, with wet legs. So , the tiles of my house became najis. Now i want to make those tiles paak. What is the correct and easy way to make it paak? What things are important to remember while making it paak? Thanks

Pour the water and remove that water then again do the same, do it three times if water is qaleel (little) inshallah it will be pak but if it is running water just once is enough.