I need to use a shortcut in order to enter the Euro symbol: € like Alt+Ctrl+E in windows.
What do you suggest?
It's easy! Just press the right Alt and the "E" key.
AltGr + e
Like @Jeroen said, its depends on keyboard layout. The best way that works with all the keyboards is to use UNICODE.
Every known character has its own unicode number. In Linux, you can write it holding Ctrl and Shift and typing the key U followed by the unicode number.
In this case,
€ is known with unicode
So press Ctrl + Shift + U, release Ctrl + Shift, then 2 + 0 + a + c, to confirm space
More info about Unicode numbers: Unicode characters
Press and hold compose key (see Keyboard settings), press c and then =.
It depends on the keyboard layout you're using.
"US International with dead keys" for example uses Alt Gr + 5, while "US alternative international" uses Alt Gr + e.
Other layouts might have other shortcuts.
Alt Gr+E does not work on Kubuntu (British), but it is there. It just needs turning on.
Kubuntu settings manager 5.10.5
I added € to Alt Gr+E as that option did not conflict with the use of any other symbols.