No one here can show you how to cast a circle, you need to learn and practice it yourself.
There are lots of very affordable books available on basic practices including circle casting and as has already been said, lots of free online literature that can help, but it does require you to do some research yourself.
With out proper guidence summoning anything is a REALLY bad idea. Thats hands on training you need try to find a civen near you. Seek out a local crystal shop or something they should be able to point you in the right direction of coven