If you go to synaptic any program you have nstalled on your system has a
descripton listed if you highlight it.Go to the section marked installed
files.This will show you where everything is installed and what folder. Most of
the time /usr. bin has the execute file .

After highlighting the entry, right-click on it and then click on
Properties. This will bring up an information screen with an
"Installed Files" tab.

Have you looked for your program in the Applications list on
the Menu Bar? If you have installed a program, it is quite possible
that it won't be on your Desktop. You might try searching for it in
the File System.

You'd be correct with the green square meaning a package has been
installed. LINPAC is not in my repositories so no idea there. MINICOM
is a serial communication program - maybe installed if you had a
device on your serial port.

You are probably doing nothing wrong. Not all of the packages in Synaptic are
programs. Some are libraries and as such would not be executable or have a menu
launcher. If it is a program, but runs from the commandline, you won't get a
menu launcher either. If the program is not completely installed you may not get
a menu item because the script has not completed. In rare cases you may not get
one if it is a KDE program, but for the most part you get KDE programs showing
in Gnome.

Not being familiar with the ones you named I can't tell you what they are and
whether you should have got a menu launcher or not.