Standard JSON string creation in creator

would you please advice how to create a string of this type using creator? the intention is to create a string that can be read by a standard JSON parser.

{ "employees" :[
    { "firstName" : "John" , "lastName" : "Doe" },
    { "firstName" : "Anna" , "lastName" : "Smith" },
    { "firstName" : "Peter" , "lastName" : "Jones" }
]}

thanks

Luis