Simple nested form question

hi, im having a 1<>N, Bol<>BolLines model, and trying to use nested
urls, but the form is confusing me…maybe someone can enlighten me:

url:
http://192.168.0.111:3000/bols/6/bol_lines/new

<% form_for @bol_line do |f| %>
<%= f.error_messages %>