You can easily add video clips by browsing for videos and audios by using the corresponding button on the timeline. You can also permanent Add videos and photos button on the Home tab. The “Import from Device” option in the File Menu where one can open the Windows Video/Photo importer which allows you to apply keyword tags and saving the images and clips in an organized fashion.
Being a YouTube creator is hard. When you're not getting subscribers nor views on your videos, it's easy to feel discouraged, disappointed, frustrated, and quit. Yes, YouTube is hard and there's a lot you need to learn in order to grow a successful YouTube channel, including video editing, audience growth, storytelling, video production, business development, and more. But when you have a mission that's bigger than all that, the motivation to keep going can be stronger than all the struggles and difficulties in the process. This is how I stay motivated on YouTube and don't quit despite the struggles.