... following along from Bob's comments:
where your 'cursor' is (touch a space on the chart in Song edit), a barline can be placed on either side of it (touch either the left or right barline button). You might also need to use the Insert button to insert space(s); this moves the measures after your cursor forwards to make room for the new space.
If you want to close up a measure to make more room on the chart overall, you can delete empty spaces in a measure with the Delete button.
e.g. a 4 space measure with two chords (on space 1 and 3) could be collapsed into 2 spaces using the delete button on each empty space (2 and 4).