[Plugin: Author Information Widget] config

Hello everybody,

I’m new to wordpress and in coding in general so i was wondering if you guys could help me.
I’ve installed the “Author Information Widget” plugin in order to have a widget in the sidebar that will also have the option to show the authors avatars, names and their last post (link) but I’m not able to code the plugins .css and the .php files.

Any help would be hugely appreciated.