Online Booking Tickets...

Today is the first time using internet to book tickets.The process is abit "chiem" to me you see.Ok I got to the Eng Wah webby and got to the movie I want to watch.But when it comesto the actula booking,I am not really sure what to do.This is the first time you see.Althought say is step by step but seems like I can only tell them how many thickets I want and just pay for the tickets.What about the seat numbers?I can't choose is it?I really don't know,don't laugh ok...So therefore,I am going there to buy tomorrow.And yes,there is this promotion saying that if you buy the combo set it is going to be cheaper.But seriously.I think there is no difference as on the spot buy too.