It's easy to find installation instructions on you tube. It's been a while since I dealt with this shifter (on somebody else' bike) so I always go online to refresh my memory. You might take a look at these two which came up instantly when I googled on "Shimano revoshift installation".
Shifter installation - the official instructions from Shimano - https://si.shimano.com/en/pdfs/dm/SL...002-05-ENG.pdf
How to install the cable once you have positioned the shifter on the handlebar