But, when I get to the part of "Now we need to install libGL", I get an error executing any of the two following commands (i.e. either if I'm using the proprietary NVIDIA driver or if I'm using the free "nouveau" one instead).
~$ sudo apt-get install libgl1-nvidia-glx-i386
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package libgl1-nvidia-glx-i386:i386 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'libgl1-nvidia-glx-i386:i386' has no installation candidate
Note: Right now, I'm just using the free "nouveau" driver, to make things more simple. So, the method I'm trying to use now is the second one, of installing something similar(?) to the "libgl1-mesa-swx11:i386" package...~$ sudo apt-get install libgl1-mesa-swx11:i386
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package libgl1-mesa-swx11:i386 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'libgl1-mesa-swx11:i386' has no installation candidate