The following example shows how to create a user using the CreateUser() method:
USING OpenEdge.DataAdmin.*.

VAR DataAdminService oDAS.
VAR IUser oUser.
VAR LOGICAL lResult.
VAR CHARACTER Paswrd = "pa3w0rd".

ASSIGN oDAS = NEW DataAdminService(LDBNAME("DICTDB")).  
oUser = oDAS:NewUser("PSCUser").
oUser:Description = "Dummy user for administration".
oUser:Password = Paswrd.
lResult = oDAS:CreateUser(oUser).

DELETE OBJECT oDAS.