Making a speech or presentation is a daunting task especially if it is for the first time. As much consideration needs to be given to your audience as to the material to be used. Explaining something to classmates is one thing, making a "best man" speech quite another. Is it a speech to entertain, to inform or to persuade?
How do you go about it? Some start with the ending, others collect lots of information and then gradually whittle it down to their perfect speech.
A third choice might be to call upon the services of a professional speech maker. There is someone available 24 /7 who writes this sort of thing all the time.