don't know why "bundle install Gemfile" does not work. You
could give a hint
I've actually already answered that for someone else right here - Bundler only works with a specific file, so you don't need to specify it.
it is not clear what to add next
Nothing complicated yet, just type
rails s -p 8000 in the terminal to start up the server, then you'll visit the page in the local browser to the right of the terminal. You'll be adding routes in later exercises