You can edit videos only using smartphone. All you have to do is taking a lot of pictures and videos as you like. If you haven't never used Google Photos, so you shold install it. I recommend this.
A lot of pictures and videos is uploaded to Google Photos by using your wi-fi network. So you are not aware of it. When you open Google Photos application, there are pictures and videos you took. And you can see some videos editted by the application. These videos are very high quality but sometimes you think you want to edit a part of this video. I'll introduce you how to edit videos using Google Photos application on smartphone.
Choose some videos to use your work. You can choose maximum of 50 videos. But when you choose a lot of videos, this application sometimes doesn't work and crashes. It is possible to use a lot of videos but I don't recommend.
Then you can watch your video. You can finish now. This video is made of your selection so it is enough wonderful. If you want to something to change, you can edit as you like.
You can choose from your devices' music or Google Photos' music.
Google Photos is ready a lot of music for you to create videos.
When you want to remove video, you tap right trashbox icon. To add, you tap left plus icon. And to edit length, you tap central scissor icon. If you want to sort, you long tap the video you want to change order.
Length of video depends this white rectangle. You can change this size of rectangle. This Rectangle means start and end of the video. When you finished edit so you tap upper right check mark.
Repeat the same things so you can finish editting. It is possible to create your video without computer. You can do it only using smartphone.