sudo apt-get install conkyPS: this command will download three packages with total 340 KB data in Ubuntu 15.04.
conky &PS: this command will run conky in the background so even if you close the Terminal Emulator it will not stop.
You can get the default configuration example in /etc/conky/conky.conf. In the beginning, you need a little exercise by editing some values such as color or update interval. Edit, then save this file, then restart conky & command to see the changes.