If you've ever used Powerpoint, then the presentation software in Google Docs is a piece of cake.
Getting Started
Select from the Create new menu the Presentation option:

The Title
Your first slide should include your presentation title, your name, the reason/location of the presentation, and the date. If you are giving a presentation at a workshop, conference, or at some place of business, you might include some kind of institutional branding to indicate where you are from. That isn't necessary for your FS101 presentations.

The Story
You should know that some of my most recent thinking about presentations comes from what I'll call the "Disney School." By that, I mean I had the opportunity to spend a time having my presentations critiqued and improved by a former Director of the Walt Disney Imagineering Corporation. And there, they learn to give excellent presentations, and it is stressed that every good presentation should tell a story.
Why? And what does that mean? Well, we all like stories. We've been telling stories (as a species) for a very long time—thousands upon thousands of years. And we spend a lot of money on stories: books, movies, you name it, we consume stories every day. Having a clear narrative makes it easier for your audience to follow, so your second slide should anchor your story.
To include images in my presentation, I often use Creative Commons licensed material from Flickr. Here, I searched for images of cars.

Then, I click on "all sizes" in the Flickr interface, find a version that is roughly 500 pixels wide, and select it. I right-click on the URL for the download link, and say Copy Link Location. (This is roughly accurate for Firefox; if you use any other browser, I cannot help you.)
I then include the image by clicking the Insert Image button, choose Specify Image by URL, and paste in the URL. When I click OK, the image is imported into my presentation.

The image serves multiple purposes: it helps to anchor my story, and more importantly, it gives the reader much-needed stimulus. We have, as human beings, been using our eyes to take in detail for many tens of thousands of years, but have only been reading for a few thousand. Pictures and diagrams are the most important part of a good presentation.

Signposting
Now, for a 2-minute presentation, you have to keep things tight. You can't go on and on. Every presentation really should have a roadmap, so your next slide is an outline. This lets your audience know what you're going to say. You've given them the narrative context—the point of the story—and now you're telling them how it will unfold.

If this was a longer presentation, I would come back to this slide every time I changed topics. I would also have an icon for each section, which would become part of my slide template. However, this is too short a presentation to use all of these techniques.
You should not dwell on an outline slide—it merely serves to orient the viewer.
Content
Keep your content visual. Minimize the number of words you use on a slide. Never stay on a slide for more than 2 minutes (for long presentations), unless you are evolving a slide through careful use of animation. Never use animation unless it serves a purpose. Under no conditions should you ever "fly in" the text of your slide one line at a time: it is a horrific, horrific practice, and I will fail any presentation that ever uses this technique. Remember that your audience has a short attention span, and that the more words you put on the slide, the more they read and the less they pay attention to you. That, of course, is a bad thing.
Practice
Always, always practice your presentation. Any presentation you give without practice will, most likely, be distracting and therefore unpleasant to the viewer. I practice every talk I give, regardless of how large or small an audience I am presenting for. It does not matter how well I know the subject, because every single presentation is a new performance. Every new audience deserves my best, and only through practice will I give an excellent presentation.
In Conclusion
That's just a few words to help get you started. We'll circle around before the end of the semester to talk more about giving longer presentations, and how to make them truly excellent.
For our 2-minute presentations, we'll be using the following evaluation matrix:

That should help remind you what fundamentals of speaking we're looking for tomorrow. The slides I created for the 2-minute presentations are below, if you want to use them for inspiration. I don't claim they're amazing slides, but they give you an idea what a minimal-text/mostly visual presentation might look like, given a short amount of time to prepare and present it. (Note, in that presentation, I also include the proper Creative Commons attribution for every image!)
