Converting iMovie long home movie into multiple labeled clips for all devices

Hello! I could use some help with iMovie. I am all updated on my Mac, iPhone and iPad. I have a 2 hour long home movie DVD. Thanks to this forum I figured out how to turn it into an MP4  using Handbrake. I then figured out how to put it into iMovie. Please note that when I read articles online or even click around within iMovie, I am not up on the lingo. I don’t know the difference between “clip” and “trim”… “segment” and “event” and “project” and so forth. Help that is very descriptive would be appreciated! Anyway, I moved it down below on my screen and figured out how to cut out unwanted segments. This DVD encompasses two years of our lives about 20 years ago so as you can imagine there is a lot of unwanted footage. Imagine a 40 minute preschool graduation and I only want five minutes in the beginning and a few minutes towards the end. So I have gone through and done all of that and what I am seeing is the bottom half of my screen has all of the clips I want with little breaks in between them. iMovie is still considering this one long movie at 52 minutes long. My goal is to have each segment as its own independent footage. I would like to label them with keywords, for example, when we went to Kahunaville, I would like to have that verbiage attached to that clip. Imagine that I am at my parents’ house and they say “remember when we celebrated Holden’s fourth birthday at Kahunaville and he fell into the birthday cake?“ I would like to be able to pull out my iPhone, search “Kahunaville “ and say “Yes I remember and here it is!“ This is where I can’t figure things out anymore. Question is, how to make each clip/section/segment become its own shorter titled with keywords movie that I can access in Photos or somewhere else from all devices? 

[Re-Titled by Moderator]