The Olympics, why do are the countries able to host the Olympic Games?

Question

I am project at the moment.

and two of my questions are?

1) Show a picture of a world map showing where each of the Modern Olympic Games has been held. [where can i find this?] Offer an explanation as to why these countries were able to host these games.

2) How is a country selected to host the Olympic Games.

Thank you for helping.