Casting a circle of protection is a way for Wiccans to protect themselves during magick work. Most people don't realize how important these are!!!

First, you want to decide where to create your circle.  Whether you have an altar or just a peaceful corner of your home – or maybe outside in nature – pick a place where you are undisturbed so that you can focus and work in peace.

You can create a circle of rocks or crystals, or sprinkle sea salt along the edges of your circle, or place candles around you – for example five to mark out the points of the pentacle, or four placed at the cardinal points, West, North, East and South – also representing each of the Four Elements.  It’s up to you how you like to mark out or decorate your circle!!

The next step is to conjure the pure energy that will surround and protect you.  There are as many ways to do this as there are practitioners, so you will find a way that is suitable to you and your practices.

Stand in the middle of your circle.  Relax and breathe deeply.  Imagine that your crown (the top of your head) opens up like a funnel to receive divine, white light.  Your crown is always connected to the divine and to your Higher Self, and you can open up and amplify this channel at your will. Open your arms, palms facing out. 

With each in-breath, visualise yourself pulling down pure, divine light through your crown, and as you breathe out you channel this light out through your palms to create a protective shield around you.  As you fill the space around you with this high-vibration energy you may feel a tingle or buzz, you may get goose bumps, or you’ll feel light and uplifted. Now hold one arm outstretched (the one you write with) and point to the edge of the circle. 

Spin around clockwise three times, mentally marking out your circle with the divine light.  Then raise your arms above your head and say: “I ask that the God and Goddess bless this circle So that I may be free and protected within this space So mote it be”

Read more here: http://wiccanspells.info/wiccan-pagan-articles/casting-a-circle-protection/