I need to compose a short parable about what God is like using something in my life and world that is familiar to me.

Obviously, as an educator who is not personally acquainted with you, I cannot know what are important and familiar elements of your personal life; therefore I will focus on the parable as a genre and provide some tips concerning how you might approach the task of writing one.
The parable is an important literary genre in many religious traditions, and is often quite similar to moral fables such as those of Aesop. It is usually relatively short narrative concluding with a moral point or parallel. Often used to convey religious or moral conceptions to children or the illiterate, parables are characterized by simple, direct language and use of elements from everyday life. The characterizations tend to be simple and generic. Characters rarely have names and are not individuated (they are often just described as "a laborer" or "a rich man").
For a modern parable, you might take an event or experience shared by your peers such as driving, attending school, shopping for groceries, or cooking. For example, you could contrast buying fast food with cooking a healthy dinner and use that to explain that God often requires us to do things in ways that are difficult but which end up being good for us.