All you need to do is drag the clips from the library to the timeline. You can do it one at a time, or click on one clip then use <Ctrl>+A to select all clips, then drag them to the timeline. Once your clips are there, you can apply transitions to all of them at once, or do it one at a time.
Be sure to set up the time duration for your image files under Preferences, Editing BEFORE you start dragging clips. The default is 5 seconds, but you can change that to any other length. You can also drag the left or right edge of any clip in the timeline to change its duration if you specifically want it to show for a longer or shorter period than the others.
If you haven't done timeline editing before, there are plenty of video tutorials in the Learning Center that will cover the basics and advanced editing topics as well.
YouTube/optodata
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