How to write test using appium for my android app?

It been 2 days I am not able to figure out how to write test cases for my android app.

I have setup the appium server and it is working. I am running it through command line using cmd appium. I know test cases will written inside the /app/test/package_name/ folder.

Right now I am not able to figure out, how would I write the test cases using android studio. I have follow the tutorial http://ift.tt/2hzP3mZ but in this tutorial desiredCapabilities class is missing(I am not able to figure out which library is need to import).

One more thing is I need to setup the selenium server?