You can start a terminal in Gnome by right-clicking on the background and select open in terminal.
To start a terminal in KDE, click on the box at the lower left of the screen. Select system tools and select terminal. You will be offered a choice of terminals. I recommend the Gnome terminal.
There are several buttons and menus that you can explore. But everything that you need can be started from a terminal, and that is all that is described in these notes.