These tasks should work with the default deploy.rb file. I assume you've at least read the Capistrano manual at rubyonrails.com, also, you should get your app running on mongrel first with manual booting and restarting before you try to automate.
h2. Spinner
desc <<-DESC
Spinner is run by the default cold_deploy task. Instead of using script/spinner, we're just gonna rely on Mongrel to keep itself up.
DESC
task :spinner, :roles => :app do
application_port = xxxx
run "mongrel_rails start -e production -p #{application_port} -d -c #{current_path}"
end
h2. Restart
desc "Restart the web server"
task :restart, :roles => :app do
begin
run "cd #{current_path} && mongrel_rails restart"
rescue RuntimeError => e
puts e
puts "Probably not a big deal, so I'll just keep trucking..."
end
end
There's a more complete article
on my blog.