How to upload game for online playing?

Hi....i have just completed my first game. I have few questions/doubts :

1) How to check the names of already registered games? I am not sure whether the name of my game has already been registered by anyone else or not. And will there be any problem if the name of my game matches with some already registered game?

2) Which is the best site to upload unity games?

Any kind of help is appreciated.