As I do not have provision in my computer to insert MicroSD card and write on this, 1st and 2nd step as below is much easier and also worked fine for me.
1. Insert the microSD in the Pocketbook.
2. Connect the pocketbook to the computer using the USB cable and when the pocketbook drives appear on the computer, copy the upgrade image (file named SWUPDATE.BIN) to the root of your memory card. After it is copied, disconnect the pocketbook from computer.
Other steps continue as above.