adding users to roles and making inactive users active

i am using visual studio 2005 and SQL Express 2005 with VB as the code behind
i am using the inbuilt membership and roles to create users
a new user create wizard is used to create users . i have set the DisableCreatedUser property to false so that all the user accounts by default are inactive

now i want all the inactive users to be listed in a list box
how to list all the inactive users programmatically?
now in a button click event , i want the selected user in list box , to be added to predefined roles
how to add users to roles programmatically ? 
please help me 
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