forms - initial migration with ruby project -

when run initial migration "new.html.erb" file each of models. simple looking form, "new.html.erb" contains following code..

<h1>new city</h1>  <%= render 'form' %>  <%= link_to 'back', cities_path %> 

now want modify page, dont understand whats going on here, in project 'form' located?

the form located under app/views/cities/_form.html.erb.

i suggest read this page before start working ruby - give better understanding of how things works.

since rais works on convention on configuration, have bad time trying figure out yourself. however, once used conventions, have fast development speed.