Problem with understanding to change theme

Hi everyone. It is my first post. It is my first use Grav CMS, and after many try I decided to ask Grav Community.

I can’t understanding whole process from add new form to admin to show data (from this form) in frontend. My english isn’t so good, so please if somebody can it mayby could write few words to explain it.

Especialy important to me is show who files I have to change to do what I want.


Best Regards