I would assume Glib and gtk and all the dependencies would come with Ubuntu.. Am I wrong? If they do, where are they? And why does everything I try to install not find them.

No package 'glib-2.0' found
No package 'atk' found
No package 'pango' found
No package 'cairo' found

Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.

1) Applications are supposed to be installed with
'synaptic' or by using the command
'sudo apt-get install <package>'

2) No package 'glib-2.0' found... means : missing libglib2.0-dev
( Already answered in your previous thread.)

No package 'atk' found .. means : missing libatk1.0-dev
No package 'pango' found .. means : missing libpango1.0-dev
No package 'cairo' found .. means : missing libcairo2-dev

All easy to find with the 2 search functions in 'synaptic'.

3) Knowing what is installed : please do this command ..
'dpkg --get-selections > my-packages.txt'
to get a text file in /home/"user" with all installed stuff.

4) PKG_CONFIG files are in the " -dev " packages too.

But no need to compile anything ? Synaptic : 26,000 packages available.
.....