Zenity installation:

* Debian (and Ubuntu) based systems:

sudo apt-get install zenity


* Red Hat (Fedora) based systems:

sudo yum install zenity


* SuSE based systems:

sudo yast install zenity


These are 3 the most common ways of installing software from terminal. You should check what package system is used in your distro before installing anything.
If you cannot see Hash Checker's icon on your desktop, please check your home folder or ~/Desktop folder inside it and manualy move it to any place you like.
Thank you for using Hash Checker!

May the Force be with you!

Cooleech