adding a note to the last one, but with a different duration

Hello,

I don't know how it is called in english when you play 3 notes with one hand at the same time (organ, piano). But, I would like to play a whole note (C) together with an half note (E); after the half note E follows a half note F.
In the demo of MuseScore there is an example in the 9th measure. How can you do this?

Pascal