Moving notes horizontally?

Hi folks - I DL'd this software yesterday, and am finding note entry challenging. For example, I am trying to create a 4/4 bar with a quarter note on the first beat and an eighth note on the last half of 4, with rests in between. However, there seems to be no horizontal movement available (to move the 8th note to the 'and of 4'), so it gets stuck somewhere in the middle. How do I change the horizontal placement of notes?