This is just some suggestions, like you said, no one can write your speech for you, and you wouldn't want them to.
One thing that helped me more than anything else was realizing that you don't write a speech by starting on the first word, then the next word, etc. The first words are the introduction. How can you introduce something you haven't written yet? How could you introduce someone if you didn't know who they were yet? So first you have to have something you want to introduce your audience to.
That means that first you think about your subject and write down all the things you already know and want to tell your audience about. Get them all on paper. Look up the things you want to and write them down, too. One good way is to cut up a piece of paper into 1" or 1"x2" squares and putting one thing on one square. Then you can add things, shuffle things around, easily, and then lay a long piece of tape over them to hold them together in order when you are done, until you put them in final form on another paper, your PC, etc. This lets you get started right away with what you know.
Then you can write your introduction. It should be interesting, and let them know what the speech is going to be about and, if you can, why they will be interested in it or how they can use it or what it has to do with them. Not exactly in those words, you can have some fun with it if you want. For example, "How to..." is popular, so you might say, "This is how to keep a gamer happy, how to get him to put it down and play football, or eat supper, or take you to the movies. It's going to be pretty hard, because..."., or, "It's really not too hard, if you just remember that..." Get the idea? You included the guys, the girls, parents, so you didn't leave them sitting there listening to a speech that wasn't about them.
You conclude by quickly summarizing what you told them in the fewest words you can, giving the audience something to do with what you just told them, or showing how to use it, for example, or telling them what it all means or boils down to. And since it's gaming, you can have a little fun with that, too.
Hope this helps you to get started!
Best regards, Mike