Minesweeper Terminal Game

I have created my very first terminal game and I have chosen Minesweeper.
I enjoyed a lot trying to figure out the functions needed to build it, and happy to be able to finished. However I have troubles to create classes. My first idea was to create a board class, however I finally did not implemented it. I still do not have the clear ideas how I could write a better and cleaner code with a class.
I will still work on it, because I want to improve my programming skills. So I am absolutely open to sugestions.

Here is my code:

Thanks a lot!!