Create a .desktop file: cannot find the icon on my desktop

I am trying to install Firefox Dev and followed this: How do I install the Firefox Developer Edition?

I created, with nano, a file: firefox_dev.desktop in ~/.local/share/applications/firefox_dev.desktop

[Desktop Entry]
Name=Firefox Developer
GenericName=Firefox Developer Edition
Exec=/opt/firefox_dev/firefox
Terminal=false
Icon=/opt/firefox_dev/browser/icons/mozicon128.png
Type=Application
Categories=Application;Network;X-Developer;
Comment=Firefox Developer Edition Web Browser.

And I'm stuck; how do I launch it?

2 Answers

Just log out and then log back in… That should do the trick!

Low-quality queue reviewers: That's it as per comments...

Make sure your that your path of Exec,Icon and other paths are correct. This are the contents of my firefox.desktop file.

[Desktop Entry]
Name=Firefox
GenericName=Firefox
Exec=/home/myapps/firefox/firefox-69.0.1/firefox/firefox
Terminal=false
Icon=/home/myapps/firefox/firefox-69.0.1/firefox/browser/chrome/icons/default/default128.png
Type=Application
Categories=Application;Network;X-Developer;
Comment=Firefox Developer Edition Web Browser.

where firefox at the end of "Exec" is "ELF 64-bit LSB executable", make sure that you mention that too.