How to work with tabbed signup/signin form using devise in rails

I am a new to the whole rails environment and learning to implement 'devise' gem for my project. Currently I have a tabbed signup/signin form.

I have generated the devise views and modified the /app/views/devise/sessions/new.html.erb to show this kind of tabbed form.Now functionality wise everything working fine. But there are several issues.

1. When I am hitting http://localhost:3000/users/sign_up it still shows the devise old signup form. I want to show the same form with the Registration tab activated.
2. On the Register tab if I submit the form with some error (Empty Email/Password), it is again redirecting to the default device registration form to show up the error messages.

I just want to get rid of this default registration page and want to use my Register tab for all signup purposes.

This question may sounds very basic, but I have no idea how to customize it. Please help.