How to set a string based on a random number in a foreach loop

I want to add a variable to a list but set it too a random string out of a set of three strings, i want to do this in a foreach loop. I am new to programming.

This is just an example:

        foreach (List li in list)
        {
            if (li.name == "name")
            {
                rand = RandomNumber(1, 4); // Random is called in 
                                              different method

                if (rand == 1)
                {
                    newName = "bob";
                }
                else if (rand == 2)
                {
                    newName = "ben";
                }
                else if (rand == 3)
                {
                    newName = "dave";
                }

                class2 obj = new class2(newName, middleName, surname);
                List2.Add(obj);
            }
        }

Every time i print out each object in the list it will set newName to the same string, I want newName to be different