how to add a new custom field in contacts

[mayu]

Hello,
i want to add a new custom field which should be present for all contacts.

I tried designing a new form by going in
tools-> forms->design a form.
Problem is that it cant be used for all contact.

i want the newly added custom field to be available on main page of contact
whenever i say new contact from toolbar.

Is is possible to do it? Please help me...
Thanks.....