Notes with varied lengths in a bar

Hi All, I'm new to Musescore and trying to do my first arrangement here. What i need within one bar while a chord is to be held for the duration of the bar (3/4 time so dotted half note), I also need 3 quarter notes to be played at the same time(in the same clef - obviously:). Can't seem to work that out how to add the dotted half after adding the moving quarter notes. Seems to be mutually exclusive. Appreciate any help.
cheers
Abs.