How to use RNGCryptoServiceProvider to get a random number greater than 256?

How to get a random number greater than 256 using RNGCryptoServiceProvider ?

Code:

private static RNGCryptoServiceProvider rngCsp = new RNGCryptoServiceProvider();

byte[] randomNumber = new byte[1];

//Fill the array with a random value.   

rngCsp.GetBytes(randomNumber);