Roles and Security in Ax 2012

System administrator -> common -> users-> users

Create new role for Form display methods
Go to Menuitems and create new menu items

1. Go to security->privilage and create new privilages
go to properties of the privilege and put the name of form and label accordingly
open the privilege -> Entry point
right click on it and create new entry point
name the entry point and put the object type as "MenuItemDisplay"
and put object name as required(i.e the Display MenuItem that is required)
and put access level as "Delete"

2. Go to security->duty and create new duty
go to properties of the duty and put the name of the duty and label accordingly
go to security->duties->DutyThatYouCreated->privileges
right click on it and create new privilege
go to properties and put the name of the privilege

3. Go to Security->Roles
create new role and put the name and label it as you require
open the role and go to duties create new duty and name it accordingly
now go to privileges and create new privilege and name it accordingly
now save it
now you can see your role for assigning to users

NOTE:-
ye grouping hai basically,menuitem ki grouping kar ke privilege banate hai
jaise 5 privilege bana liye,uss mei se ek duty bna li usmein 3 ko privilege de diya
phir dusra duty bna liya uss ko 5 ka privilege de diya
phir roles assign hote hai user ko