When you start a new PowerPoint file, you can either create a blank presentation or a template. Blank presentations allow you to apply your own style, but this can be a time-consuming process. Templates can give your presentation a uniform style, but they may not suit your exact needs.  You can edit any aspect of a template, so feel free to choose one that mostly matches your vision and tweak it as you see fit. You can apply themes to your project at a later time after you've added content. Click the Design tab and select a theme. It will be immediately applied to your project. You can either undo it (Ctrl + Z) or revert to a blank theme if you don't like it. You can access templates from the File tab. Click New and then browse the available templates. You can also download additional templates from a variety of resources online. Your title is the first thing that your audience will see. It should be easy to read and give a basic overview about the topic of the presentation. Most presenters will include their or their group's name on the title as well. Press Ctrl + M for a new slide. A blank slide will be added after the slide you are currently on. The slide will contain a title box and a text box. You can choose to use these or insert your own objects using the Insert tab.  When adding a text box, you can click and drag to make it whatever size you'd like. You can then adjust this later by grabbing one of the corners with your cursor and then clicking and dragging again. You can click on any text box and start typing to begin adding text to your presentation. You can format text just as you would in Word, with formatting options available in the Home tab. You can use the frame on the left side of the window to quickly scroll through your slides. Clicking any of them will open that slide so that you can edit it. You can click the Outline tab to see an outline tree of your presentation. Each slide will be labeled by the slide title. You can get a basic feel for the flow of your presentation at this point by...

TL;DR in Vietnamese:
Chọn giữa bản trình chiếu trống hoặc theo mẫu. Đặt tiêu đề cho bản trình chiếu. Thêm slide mới để chèn nội dung. Điều hướng bản trình chiếu. Xem lại bản trình chiếu.