Why the hell is my tile palette not working?

I am an utter and complete Unity noob and I have absolutely no clue what I am doing. I’m trying to do the RPG tutorial, but I’m stuck very early in the process. I can’t use the tile palette. I can open it and see it, I can make selections, but I am completely unable to use it to paint into the game. What the hell am I doing wrong?

i was on the game tab instead of the scene tab.