Mental Projection is a trance like state that is very easy to obtain.
Sit down and if you can meditate for a few minutes just to get your mind ready to wander. Now think about the many places you'd liek to visit. Imagine them flying past you. Make sure your eyes are closed though. Look forward in your mind and picture a tunnel with images of these places flying by. What do you see? What does this tunnel look like? Do you naturally see anythign you didn't think to imagine? Write these down in a personal notebook or diary w/e, for they will give you a bit a reference for later on in lessons that take you in more depth.
Think about these things that you saw. Each little detail as you are falling asleep that night. Try to keep these things in mind as you doze off into sleep. And as you sleep try to keep conscience ness as you sleep. During your sleeping try to imagine a doorway. Any kind at all. Decorate this doorway with your own personal images or decorations to make it spiritually attached to you. Don't forget a dorr handle though it may be useful. Now, if you can, slowly bring yourself back awake. Now write everything you just saw in your dream. Including a miniature drawing of your door. If you feel like coloring the door this may be even more helpful later on when trying to come back to it. Did you see anything in your dream that you saw earlier when you were meditating? Write it down...
If this doesn't work the first, becasue you either couldn't keep control or train of thaught during your dream or even if you couldn't meditate, it's o.k. A lot of people, or rather most people can't dream control at first try. And many people have a hard time relaxing enough to meditate. Just keep at this for a while until your door becomes more and more vivid.