Here is one way to do it if you want 0x00002020
Index=(Index>>8); //this gets rid of the AB so you have 0x00000020
Index|=(Index<<8); //this keeps the 20 at the end and assigns the previous // two bytes. now index=0x00002020
I hope this is what you were looking for. Just practice shifting. When I first did it, I could not understand a thing. Now I actually am getting how to use left shifting,right shifting,or,and and xor operation.
To better understand shifting, I recommend simply using Python's interpreter b/c there is no need to even compile to see how shifting works.