When you are dreaming about entering the new doors, then such dream indicates the new chances the life is going to provide to you. You are going to the different phase of your life. If you see the doors that open to the outside, then it shows the necessity to be more opened to others. If the doors open to the inside, then it means you should look deeper into yourself, how you feel and what you want out of life. The dream, in which you see the doors that are locked and you are unable to open them, represents the opportunities you are unable to have. Perhaps the life has closed some of the choices you could do. The back door you see in a dream, indicates the hidden aspects and secret thoughts and ideas. If you have closed the door to someone, then it shows you are no longer giving the access to your life to that certain person. If you see the front door of the house or any other place, then it shows your communication skills to the outside world. If you left the doors open, then it means you are open to new ideas and opportunities the life has prepared to you. If you see the doors that are made out of glass, then it shows the invisible shelter you have while dealing with your daily life and people that includes it. If you see the house or any other place that has no doors, then it means you are unable to escape some situation in your waking life. The dream, in which you see someone waiting at the door, signifies your attitude towards that person and the fact if you are going to open it for him or keep it closed. The dream, in which you see the side doors, shows some situation you wish to escape while being unseen. The doors of the car, denotes to different meanings: the doors of the driver shows that the dominant person you are, and the passenger doors indicate the situation you are leading made by somebody else.
Read more about dreaming of Door in other dream meanings interpretations.