It depends entirely on the operating system "image" you choose to run on your compute engine instance. There are many, as listed at
https://cloud.google.com/compute/docs/operating-systems/ , and you don't tell us which one you chose, thus making it impossible for us to help you.
In general, to install/update OS components, you SSH into your instance, then run a command depending entirely on the operating system you're running -- *exactly* like you would do if the OS was running on a physical machine. For example, if the OS you chose is debian, the command would be apt-get -- see e.g
http://linux.die.net/man/8/apt-get -- no matter whether you're running debian on GCE, on your workstation, or whatever.
Alex