Do you like making videos?

More and more people enjoy making videos and vlogs now. I wanna do the same and make a video with photos and videos for my 90-year-old grandpa as a birthday gift. This is my first time video-making experience.
But the problem now is, I don't know where to find music and how to add music to the video on my computer. I can do it easily with my phone because there are many excellent video editing apps now. However, I think that doing this on the computer, the quality can be better. Then I searched online and found some tutorials. Most of them suggest me download Spotify to MP3 fisrt via some tools like DRmare, AudFree Spotify Music Converter. I havn't tried them , so I don't really know how well they perform. Then I see a few video-editing software like iMovie, Premiere Pro and Camtasia. Did anyone try those? I want to find the most user-friendly one, considering I am a newbie. Feel free to share you opinions and thanks a lot!