I am a year 10 student needing to deliver a persuasive speech about any of the following Australian public holidays: ANZAC Day, Labour Day, Queen's Birthday or Australia Day, and convince my audience (teacher and students) to accept my viewpoint of why this specific holiday reflects our identity and who we are as Australians. I have chosen ANZAC Day. The finished work is to be 4.5 to six minutes in total, along with a PowerPoint presentation alongside and no word count (just thought I'd be specific). I guess my main problem is with the introduction paragraph and concluding paragraph, more so the concluding one. I want to start in a way in which my audience will really want to listen to, and finish in a way that'll really get them thinking about what I've just presented. In other words, what would be the best possible way to structure a persuading introduction and conclusion that will capture the attention of my audience?

I can definitely offer some advice on this topic.  I have been teaching a public speaking course for almost a decade.  From the information provided in the question, it seems like you have a good handle on the persuasive arguments that you plan on using to convince your audience of the importance of ANZAC Day and why it accurately reflects who your audience is as Australians.  That’s great news.  That means that you have the majority of your speaking points ready to go.  
I do agree with you that the introduction and the conclusion are the more difficult parts of the speech.  I spend more time teaching introduction and conclusion tactics in my class than any other speech topic.  The question specifically mentions that you want to get your audience listening right from the start.  That’s absolutely critical. Audiences that are bored right from the start do not continue to listen.  That means the very first sentence of the speech needs to grab audience attention.  I call this part of the speech the “attention getter.”  I teach my students 5 types of attention getters.  
Ask a question.  This is probably the easiest way to begin a speech.  You could go with something simple like "Why do Australians celebrate ANZAC Day?"  You could increase audience participation by phrasing the question a bit differently.  "How many of you know why Australians celebrate ANZAC Day?"  This question style would require audience members to raise their hands.  Regardless of the question, by asking a question, you are activating the brains of your listeners.  The audience knows that you aren't looking for a verbal answer, but audiences can't help but begin thinking of an answer to the question.  That focuses their attention on the topic, and it focuses their attention on you because they want to hear the answer and find out if their answer is correct. 
Use a quote.  Quotes are effective because more often than not the chosen quote is a quote from a well known person.  That always carries weight with audiences.  If the quote isn't from a well known person, that's okay too as long as it is focused on your topic.  The quote still does the same thing for audiences.  They assume that the quote is of critical importance because you have chosen to start with words that are not your own.  Audiences will be curious about why that particular quote is so important, and curious audiences will continue to listen. 
Make strong, bold, and perhaps controversial statements.  The goal here is to get an emotional response out of audience members.  This can often work better than trying to trigger logical responses from audience members; however, be careful.  The bold statement can backfire by creating a slightly hostile audience.  That audience will either not listen to you or will not be easy to convince, because they already think you are wrong.  
Use a definition.  This is similar to a quote in a lot of ways.  It presents your audience with something concrete and factual.  It generally focuses the audience to your intended topic; however, I personally feel that it is the most boring.  It can be done well, but it tends to be a bit of a flat way to start. 
Use an anecdote (tell a story). This type of attention getter is not a single sentence.  It involves the speaker "setting the scene."  Considering your topic, you could tell a story about something that happened during the Gallipoli campaign of 1915.  You could also tell a story about yourself and the way that you and your family celebrate ANZAC Day.  Audiences love stories.  That's why anecdotal introductions are so effective. 
For the conclusion, you've stated that you really want your audience to "think" about what you've just presented.  That's definitely true.  You are going to do this by signalling to your audience that you are finishing your speech.  Saying "In conclusion" is a simple and effective way of doing this.  Then restate the main persuasive points in a succinct way that is not an exact repeat of what you have said earlier.  I would attempt to try to get your audience to do more than "think" about what you have said.  A good conclusion to a persuasive speech is going to motivate your audience to do something.  Perhaps you can encourage the audience to go to a formal city celebration of the day in order to publicly celebrate with other Australians.  
Also in the conclusion, you might want to think about using one of the attention getters as the final statement.  Closing a speech with a quote is always an effective closing.  Finishing with an anecdote can be effective as well, but be sure to keep it short. Asking your audience a rhetorical question is also a good closing technique.  "For me and my family, we are going to celebrate ANZAC Day with hundreds of other fellow Australians.  How will your family choose to show pride in this great holiday?"   
https://www.mcckc.edu/tutoring/docs/br/english/Speech_Outline.pdf