On my Pixelbook cURL was already installed but check to make sure first.
curl -V
You should see some output like this:
curl 7.52.1 (x86_64-pc-linux-gnu) libcurl/7.52.1 ...
If not you'll need to install it:
sudo apt-get install -y curl
Then from your home directory:
curl -sL https://git.io/fNbqF | bash -
At this point Firefox should be installed and you can start using it from
the shelf or by typing firefox
.