It is an INTRODUCTION to the judge or hearing's officer. It introduces your case and identifies all the relevant issues. Highlight the issues and tell the judge how you will prove them in your favor.
Caution! Do not spend a lot of time on the opening statement. Remember, evidence wins cases, not fancy speeches. You are not telling a story to the judge like how you tell a story to a friend. Focus on the facts.
For example, in a lardlord/tenant dispute dealing with security deposit, you may say "Your Honor, this is a case of small claims for $1200 security deposit that has not been returned to me and it has been after fourteen days of my move out on December 10, 2016. I provided Mrs. K, the landlord, proper notice of thirty days, left the place clean and with no damage."
Another example is, in a breach of contract dispute, you may say "Your Honor, this is a matter of Mr. Adam who we hired as a plumber for our bathroom and did not finish the work after I paid him the full amount of $1000 on September 29, 2016."
Remember: Plaintiff will give his or her opening statement first, followed by the defendant. Judges sometimes will delete the opening statement so be ready for any possibility.