How to set menu item of software in main menu in centos 7 linux.

 for example we are setting menu for firefox-108.92. First extract it as I did in "/opt/firefox"
then write as following in gedit and name this file as : "firefox.desktop". This is menu shortcut in Linux. If you double click this file firefox web browser will be oppened. To edit it open in gedit.

firefox.desktop:-
-----------------
[Desktop Entry]
Version=198.92
Type=Application
Terminal=false
Exec=/opt/firefox/firefox
Name=Firefox
Comment=Internet Web Browser
Categories=Network;WebBrowser;
---------------------------------

Here file name in "Exec" entry last "firefox" is executable file in folder "/opt/firefox". Remember we extracted firefox.tar.gz here in path : "\op\firefox". You can also set "Icon" by giviing full path name of "Icon File".

Now Save it to path folder : "/usr/share/application" as: "/usr/share/application/firefox.desktop". After you saved file in "application" folder, file name will be displayed as given "Name" item in ".desktop" file, here in our "firefox.desktop" file in "Name" entry is "Firefox". So in "application" folder file name will be shown  : "Firefox". This will add in menu as Universal access menu. If you want to add in "user account", or local menu entry, save ".desktop" file in path : "/home/user-name/.local/share/applications", as mine path is : "/home/rahul/.local/share/applications". That will add in local menu. That will add in local menu.

To put in internet category, you should add "Categories=Network". To know what "Category"  is, for perticular ".desktop" file for it's application, you should check in "/usr/share/application" and search nearest application desktop file. To do that see for example in our case i saw in menu near is "Ekiga Softphone". Now in "/usr/share/application" search for "Ekiga Softphone", open it in gedit and search for "Categories" tag and copy all tags following "=", and paste in our ".desktop" file in "Categories" tag. This "Categories" sets our menu item in place whre it should be shown. In our case "Apllication->Internet->Firefox" menu.

That's all.