How can I paint using landscape tool?

How can I paint using landscape tool? I’ve created a terrain, gave it a material, selected the paint tool but there was no place to select the material. I’ve tried to select or drag and drop my other material (a different one from the landscape) and try to paint but it doesn’t work… can anyone please tell me how to use the paint tool in the terrain?

Good day,
Follow this guide step by step and you should be good to go.