ushort data = 0b0000000000000000;

// turn on all the bits
data = data.SetBits(0, 16); // value is now 0b1111111111111111

// this is the equivalent as above
data = data.SetBits();

// Clear the middle 4 bits.
data = data.ClearBits(4, 8); // value is now 0b1111000000001111

// Toggle all the bits.
data = data.ToggleBits(); // value is now 0b0000111111110000

var finalData = data;
// read the upper byte
var upperByte = (byte) data.ReadBits(8, 8); // upperByte is now 0b00001111

// write 0b1011 into the upper nybble
upperByte = upperByte.StoreBits(0b1011, 4, 4); // upperByte is now 0b10111111

// chaining operations, the same steps and end results
data.ClearBits();
data = data.SetBits(0, 16)  // value is now 0b1111111111111111
           .SetBits()       // this is the equivalent as above
           .ClearBits(4, 8) // value is now 0b1111000000001111
           .ToggleBits();   // value is now 0b0000111111110000

upperByte = ((byte) data.ReadBits(8, 8)) // extract the upper byte (0b00001111)
  .StoreBits(0b1011, 4, 4);              // store the value in the upper 4 bits, now upperByte is now 0b10111111

// finalData 0b0000111111110000
var beByte0     = finalData.ReadByte(0, Endian.Big);              // 00001111
var leByte0     = finalData.ReadByte(0, Endian.Little);           // 11110000

var mutatedData = finalData
                 .StoreByte(0b10111111, 0, Endian.Big)
                 .StoreByte(0b01010101, 0, Endian.Little ); // lower byte is now 0b01010101
;                                                           // mutatedData is now 0b1011111101010101

var beBa = mutatedData.ToByteArray(Endian.Big); // beBa=[0b10111111, 0b01010101]

var leBa = mutatedData.ToByteArray(Endian.Little); // leBa=[0b01010101, 0b10111111]

var leBaToUInt16Le = leBa.ToUInt16(Endian.Little); // leBaToUInt16Le = 0b1011111101010101

var leBaToUInt16Be = leBa.ToUInt16(Endian.Big); // leBaToUInt16Le = 0b0101010110111111