That means that every other distro you have tried is non-free. Since Trisquel
is a free replacement for Ubuntu, including non-free software would defeat
the purpose.
You are of course free to install whatever software you choose on your own
machine (Trisquel doesn't impose restrictions like some non-free systems),
including the proprietary driver for your WiFi card, but it would be against
community guidelines[1] to help you do so, so the best advice I can give is
to use a USB dongle. I have one, and it works great.
[1] https://trisquel.info/en/wiki/trisquel-community-guidelines
