Usually, the binaries of the programs that you download are located in
/usr/bin, along with some other directories that could hold these binaries. You can tackle this through several ways.
Transmission is located in
I'm no expert in this, but here's how I would go about locating where transmission is:
First, you need to know what exactly is the name of the application, the name of the binary, because it might not be a straight-forward
transmission. So, you could simply do
ls -l /usr/bin | grep transmission. This will output all the files that have
transmission in them. When I execute that command, I get this:
alaa@aa-lu:~$ ls /usr/bin | grep transmission
gtk usually denotes that this is a "graphical" program, so there you have it, Transmission is located in
/usr/bin and it called
transmission-gtk. So, browse to that file when you're opening your torrent file, and it should work.
If you don't get any output from the above
ls command, then
transmission might not be installed in the first place. You can check if it's installed by using
alaa@aa-lu:~$ dpkg -l | grep transmission
ii transmission-cli 2.77-0ubuntu1 i386 lightweight BitTorrent client (command line programs)
ii transmission-common 2.77-0ubuntu1 all lightweight BitTorrent client (common files)
ii transmission-gtk 2.77-0ubuntu1 i386 lightweight BitTorrent client (GTK interface)
This tells me that
transmission-gtk is infact installed.
If you didn't find it in
/usr/bin, you can use the command
alaa@aa-lu:~$ whereis transmission-gtk
transmission-gtk: /usr/bin/transmission-gtk /usr/bin/X11/transmission-gtk /usr/share/man/man1/transmission-gtk.1.gz
Ignore the other two locations.