Create file in ~/.local/share/applications/Postman.desktop
[Desktop Entry]
Encoding=UTF-8
Version=1.0
Type=Application
Name=Postman
Icon=/home/ducnt114/Downloads/Postman/app/resources/app/assets/icon.png
Path=/home/ducnt114/Downloads/Postman
Exec=/home/ducnt114/Downloads/Postman/Postman
StartupNotify=false