Re: Too smart in 'general forum' to answer so I try here....
If there's no installer, you can just leave it in your home folder and run it from there.
If you want it to be accessible by other users on the same computer, you can put the whole folder into /opt.
Either way, you can add a "menu item" to it by using the Main Menu utility in Ubuntu, which will then allow the program to appear in the Dash, and you can add it to the Launcher in this way too.
But to answer your precise question, if it doesn't install itself to anywhere, then it can go anywhere. It'll happily sit wherever you put it, including your home folder or Desktop folder. If there was a "best" place to put it, then the program would have had an installer to put itself there.
I try to treat the cause, not the symptom. I avoid the terminal in instructions, unless it's easier or necessary. My instructions will work within the Ubuntu system, instead of breaking or subverting it. Those are the three guarantees to the helpee.