Tor can be launched from the dash. The usual problem is that the path to "start-tor-browser" is messed up. Check the command line under "properties" to see if it is correct. If this doesn't work and you used the Tor Browser Bundle, check your download to be sure that you actually decompressed all your files. Find and click the "start-tor-browser" file. If Tor does not start, something is still compressed. When you can start the program from this file, your problem is in linking to the launcher properly.