The first thing you have to do is become lucid in your dreaming. You need to stop in the middle of a dream and say, “Hey, I’m dreaming.”
Then you need to find a wall, preferable one within the dream that is felt to be imprisoning you.
Then realize in your lucidity that you have to walk through the wall.
Next, realize that there is no wall. It is only a thought and has no existence as a solid wall. Make that realization within the dream.
Then lean against the apparent wall. Lean into the apparent wall. A resistance may be felt, but a certain kind of momentum will be generated to take you through the wall and into another dream space.
Where you go from there and how you apply lucid dreaming to your thoughts and your self-image in the waking world is the stuff of spiritual searches. Good luck!