Foren / Cotonti / Support / Structure desc to textarea

I want to make the category's description field to a textarea with textboxer(in admin pannel).
Tell me please how to make it?

I'w changed in the DB its type to 'text',but i dont know how to put the textboxer window in the in the 'Create new' (http://cot4/admin.php?m=page&s=structure)