The best way to approach this type of retrospective is to get the team to reflect on milestones, points of change and lessons learned over a specific time period.
The board is split vertically into three rows – this allows the team to indicate how well they felt events went on a scale. You could use the defaults: Excellent, Good, Bad… or change the labels to your own.
The board is also split horizontally into three columns – each column indicating a distinct period of time. This is helpful to get the team thinking in chunks of time. Try to imagine the split between each column as a particular milestone or event.
It's helpful to give time at the start of the exercise for the team to brainstorm and remember events. Once they have written down their thoughts, have everyone add them to the board chronologically and according to how well they feel the events went according to your scale.
Finally, talk through everyone's stickies as a group. This template is really here to facilitate a good discussion