Custom icon

I want to make some custom icons, but need to know the size to make the transparent gif? The existing icon was displying as 32×32 but this includes a large amount of transparency, so my icons appear bigger.

Next I would like to know where custom icons are uploaded to? I have made a custom social icon and link but now need to change the icon, where can I find it? I looked in media library and nothing. I looked in “/wordpress/wp-content/plugins/easy-social-icons/images” but also only the default images, not my custom icon/

Thanks,
Andy

https://wordpress.org/plugins/easy-social-icons/