After extracting the tor-browser.tar.xz, I found there are two things in the tor- browser folder. One is a Browser folder and the other is a start-tor-browser file, which I used to be able to open as a executable file in Linux Mint, but this time I was on Ubuntu. How can I make start-tor-browser an executable file to start Tor Browser with, so that I don't need to launch the Tor Browser using the terminal every time.
From the command line you can make the file executable by running:
chmod +x start-tor-browser.sh
start-tor-browser.sh is the name of the start script, which I can't remember off the top of my head).
In Ubuntu you can tell Nautilus to run the script instead of opening it in Gedit by following these instructions from Ask Ubuntu.