To edit a video for social media using easy and simple tools, try the following:
Adobe Spark – for PC, Mac and iPhone (but not available as an app for Android)
GoPro Quik video and photo editor – very simple, available as an app for both Android and iOS
Mobile Journalism Manual – this is a fantastic resource for making videos using your mobile phone
You can also try Canva, Animoto, Movavi, Power Director. Here are some reviews for editing software:
Top 5 Free Video Editing Apps For Your Phone! https://www.youtube.com/watch?v=Hd1AXogH8_g
Try to always use picture that are a large size, at least 800 pixels on the shortest side.
Also try and use pictures that are creative commons or public domain, so there are no copyright problems in using them. You set your image searches for this option. Here are some good places to search: