Im a bit nervous as i never talked to more than 3 people at a time
As someone who had a "day job" standing up and talking to people on technical subjects, I offer the following advice:
Know what you want to say, work it out before hand.
Make notes to remind you of the things you want to say, and to keep it in the correct order. Just simple "bullet points".
DO NOT write a speech and read it out from a sheet of paper. This is something which will kill it stone dead!
If you have a practical demonstration, rehears it beforehand, ensure that it works reliably.
You are the expert, your audience knows nothing about the subject.
Keep it simple.
Don't talk in TLAs and jargon.
Look at the audience as much as possible. Don't just keep your head down looking at the notes or the demonstration piece.
Enjoy yourself, learn from the experience.
Engineers who can stand up and make a good presentation are rare. This could help add another string to your bow.
JimB