The hardest part of composition can be getting started, so let's try to put the pieces together.
The thesis statement is going to be the main idea of your paper. You already chose to describe a volleyball regional game as your topic; therefore, your task is to create a sentence that encompasses all that information.
Some starting phrases could be;
Last week's volleyball regional game was the most important of the season...
In our school volleyball season is of great importance...
to this add as many details about the game as you can remember. Introduce who played against whom, why was this game important and what was the outcome.
Remember you still have 3 body paragraphs of volleyball description to write about.
And don't forget to write a good conclusion that reflects what you wrote in the intro.
I hope this helps