I need help in using appium 1.6 with python client in Mac

So the problem is that I have installed everything that was mentioned in the website except the android emulator. I’m testing an iOS app but I’m getting an error stating that my platformVersion is not in the list of simctl sdks. I really don’t know how to resolve this issue. Also How do I write test cases for python? Can someone provide me with a link for sample test cases? how do I run them? I’m new to automation and I’m really overwhelmed by the amount of information that I have to grasp in order to proceed with this.