This works for me with MacBook Pro 17in mid 2010 iMovie 9.0.9. OSX 10.12.4
Simple system. If you are starting from scratch. Description here more complex than implementation.
You should be able to create a new project and then simply drop photos in from a finder window.
Then you can adjust the duration of each image either by double clicking for properties or pulling on the end of a single clicked image.
With that technique you can readily vary the duration of individual images depending on importance and length of your voice over.
Be conscious that if you spread the images out to a good duration for your presentation purposes, you can later adjust after you've done a voice over. If you leave gaps in a long single narration, you can add little extra notes in the gaps with additional voiceovers. And dump them with a single 'delete' But while you can erase the end of a voice over I don't think you can chop it into pieces.
Under T in the right side menu you can add titles by dragging them in to any point. Some appear together with, some between images. If you drag what you think might do to the right point it will fit in or not — if it's the type that goes with, you need to put onto a clip. If it's the type that's separate, try to drop it separately. Again you can adjust duration. Helpful if you need to offer difficult spellings. Ticker runs on the bottom in a black space, the speed of the ticker depends on the duration you set. Ticker and others that go with clips can be shifted to earlier or later.
When a project is finished I promptly export it to another location on the hard disk and backup. I had a problem with iMovie crashing recently, only solved by trashing both the events folder and the projects folder, I had lazily let them build up content. iMovie works much more efficiently after that clean-up. Fortunately all my completed movies (and still-wanted production clips) were stored elsewhere. Not all eggs in one basket!
Oh and note that there is a Ken Burns effect available under Crop, for still images. Not the Apple-defined back and forth, but possible to define where it begins and where it ends. If you want to zoom in and later out, insert the image up to five times: one full view, one zooming to the detail, the third staying with the detail, the fourth zooming out, the fifth the whole image again. Adjust lengths for comfortable and understandable viewing. (or press the space bar to pause and point to the detail :-)