Run pageant.exe, find its icon inside your system tray and add your SSH key.
Open up a cmd and put the full path to PuTTY’s plink.exe into the GIT_SSH environment variable, e.g.:
set GIT_SSH=C:\Program Files (x86)\PuTTY\plink.exe
You can then use Git like you would on any sane operating system. Just go ahead and git clone, git pull, etc.
How to use Git on Windows with PuTTY (console)