Displaying error messages

I am able to display error messages when a user tries to sign up for
my site but doesnt pass the validations, but I am having trouble
displaying them for another controller in my site. I have included:
<%= error_messages_for 'spec' %> in my view spec controller but this
only displays the single message defined in the controller:
flash[:error] = "There was a problem updating."

For my other user controller, when something doesnt pass the
validations I get specific error messages like this:
4 errors prohibited this user from being saved

There were problems with the following fields:

    * Username is too short (minimum is 4 characters)
    * Password doesn't match confirmation
    * Password is too short (minimum is 4 characters)
    * Email is too short (minimum is 5 characters)

Anyone know how to get these? And if so, how do you change the CSS of
these messages?

Thanks so much.