Well summoning is real but I would discourage even the most powerful wizard from doing it. Unless you have special permission from the being what youre doing is basically kidnapping (how would you like it if someone was to take you from your home against your will?)
Now if you want to get to know a supernatural entity you need to study up on them first (yeah I know studying sux :P). A useful race beings to get to know are angels. My guardian angel is the great healer Raphael and though I never actually talked to him I was told if you wanted to summon him you need a green candle. You first need to be friends with whatever youre trying to summon then evolve your relationship from there. The spirit world is not too much different from the real one. Take time each day and meditate on the great unknown and see what beings are willing to help you out. There is a lot more on this subject but I cant go on in detail about it. STUDY STUDY STUDY!!! If you have a more specific question I will be happy to help.
PS. summoning things is nothing like in a game. Its more surreal in nature and it requires faith to know that what you experienced was real. The more you practice the more you begin to see whats real and whats not. Only skilled magic uses can see what it is they are summoning with their real eyes. Also if you have repeated dreams and visions of supernatural creatures thats a sign that your getting someones attention (weather its good or bad thing thought depends on what they are doing)
*WHEW* a lot said but little answered...sorry :(