I haven't go but do we we need to have a reservation in order to go? Or we could go in with any trouble?

How much is the tickets

Depends on the popularity of the movie or showtime. I mean, you CAN always just walk in, but I recommend getting your tickets (and seat reservation) beforehand. It won't cost you more, and you don't have to worry about the seats being sold out.

Reserve seating when you purchase tickets.