How to pass variables in and out of AsyncTasks?

I haven't spent much time working with AsyncTasks in Android. I'm trying to understand how to pass variables to and from the class. The syntax:

class MyTask extends AsyncTask<String, Void, Bitmap>{

     // Your Async code will be here

}

it's a little bit confusing with the < > syntax on the end of the class definition. Never seen that type of syntax before. It seems like I'm limited to only passing one value into the AsyncTask. Am I incorrect in assuming this? If I have more to pass, how do I do that?

Also, how do I return values from the AsyncTask?

It's a class and when you want to use it you call new MyTask().execute() but the actual method you use in the class is doInBackground(). So where do you actually return something?