It’s okay to use other people’s words for formal definitions (e.g. slide 8) or famous quotes. However, for the rest of the presentation, you should use your own words. It’s extremely important that you get into the habit of (a) deciding for yourself what information is important, (b) what information is not important, (c) what order you should present the information in to make it easy for the audience to understand, (d) what the best way of explaining the information is etc.