Many Apple computer owners use iPhoto to manage their personal images. Here is a brief explanation of how to export images from iPhoto for use in PowerPoint or for other purposes. Click on the thumbnails below to see the full image.
First, select the images that you want to export. If you want everything in a folder or slideshow, go to Edit–Select All (image 1).
Then, go to File–Export (image 2).
In the window that pops up, make selections that match image 3. I have chosen maximum dimension of 1024 because that usually works well for PowerPoint. Most projectors currently display at 1024×768. If you know you’ll be using a projector that can project larger, then choose the larger dimension. When you click the Export button, you will need to navigate to where you want the images to be saved. You may want to create a folder in which to save them.
The Export window does allow for a lot of other options when exporting images, so you may want to explore those as well. Some additional information can be found on Apple support.