Okay, I would like to start this off by saying there is no short cuts in magic, you either devout yourself to the practice or you just don't do it. There is no easy way to learn any sort of knowledge, you must study and practice. There are no "levels" in magic, we study and we practice, we do spells we can handle and understand. Asking us how to do "summoning" spells means you are not ready, magic isn't a rush, you can't rush it, otherwise nothing will happen.
Zeus is spot on. In order to perform evocations/invocations you'll need to have learned to: enter a meditative state, sense spirits, communicate with spirits, manipulate energy and have worked through your chakras.
If you skip these starting steps then you'll get no where.