Newbie : how to write 2 notes

EDIT : SOLVED, I have found the solution. I have to use "voices" :
http://musescore.org/en/handbook/voices

I add : the documentation is not clear by saying "Click on 'Voice 2' button", it should say "Click on 'Voice 2' 1-4 buttons on the right top of the screen".

Thanks

Hello, I am a absolutely beginner in Musescrore.

I want to write 2 lines of notes as in this example :

But all I manage to write are "glue stick together notes" as :

I tried : x and shift-x, no luck.

Any idea please ?