Hi Swati,
You can create the Roles in the service Studio itself, under the Logic tab, there is one folder of "Role" where you can add a specific role for Ex "Admin". And then you must go to User's Application, you can log in to the User's app with your Outsystems credentials. Path for the same is <https://Your personal Environment/Users>. In users application you will see list of users, by clicking any one of them you will find that there is an Option to add the roles, under the Roles subheading. you can then easily assign the Admin role to that user by typing "Admin" in the input box provided to you. It will show you the app name with the Role.
now you need to check the role for that particular user so, that the user can have the role to edit the data. You must go to service studio, in your app, from where you wanted the edit data in that(Ex Button/Link). First you need to create a data action with the output parameter type Boolean and in action you need to drag and Drop the "CheckAdminRole" action associated with the role you have created.This CheckRole action has a run time output parameter of "CheckAdminRole.HasRole" of type boolean, which tells us that a particular user has a Role or not.Now just drag an assgn operator below the CheckAdminRole action and set the data action's output parameter equals the "CheckAdminRole.HasRole". Now you just need to use the data action's ouptut through which you wanted to perform edit funtionality. like the enable and visible property of a link/button.
Appending some images for your reference.




And Yes please do not forgot to go through the learning path of role based security.
Hope It helps!
Thanks