I think this article will help you. Thank you for having this question, I forgot that such a tool can go faster when we know what is on his system.
STEP 1 : Create a new file in the launcher
$ sudo touch /usr/share/applications/appname.desktop
STEP 2 : Edit this file
Comment=Comment if you want
Categories=newcategorie1,newcategorie2 <===== create your categories here