Resolving Slurs with a half note

I don't know exactly how to describe the issue that I am having, but I will try. I am trying to write a half note played by the fifth finger while the first two fingers play G and A natural as a slur in quarter notes (so the G is played first and then resolves on an A natural). Does that make sense? I cannot figure out how to do this. I have tried adding the note in manually with the mouse, but that doesn't work. I have also tried treating it as a chord, but that just gives me three half notes. Does anyone know how to do this?