Hey Tom,

You can get free graphics at a number of sites, including these:

https://unsplash.com/
https://pixabay.com/
https://www.pexels.com/

Banners and gifs:

https://steemit.com/design/@mahdiyari/1-how-to-design-animated-gifs-banners-and-images-professional-photoshop-aftereffects

For this one you don't need additional software, and it's free.

Regards,
revoltingpeasant