How do i add global stage clear counter to the game?

Hi i am making an obby. I want to display a number in map which shows the number of obby completes. I know i need to count some how the touches of last spawnpoint and store in some variable but yeah thats all i know, i couldnt figure out and i dont know how to display the number in game (like on sign or something like that). Can you help me please thanks.