Open the terminal (short code: CTRL+ALT+T).
And it should have a default solid colour as background like this.
Right click on any part of the terminal and select the “profile” option, the “Profile Preferences”.
Select the “background” tab to reveal 3 options: “Solid color”, “Background image”, “Transparent background”.
When you select the “Transparent background” option the terminal becomes transparent, you can use the slider underneath to adjust the transparency level to you choice.
That would be all for now, thanks.