The first thing that you need to do when creating your own Custom Report is to select the different widgets that you would like displayed. As you might already know, you can add the widgets that suit you best by choosing from the different widget categories available and then explore their amazing potential.
In the Campaigns Category, one of the widgets included is named "Top Custom Fields". This widget provides you with metrics regarding the total opens of your campaign, broken down by the values of your openers' custom fields. Please note that said widget can be filtered by Campaign.
1. Select the Top Custom Fields widget by clicking on the Add button and then tap on Save.
Your Custom Report has already been filtered by the most recently sent campaign, therefore this filter will be applied to the widget selected as well.
2. In case you want to change the selected campaign, tap on the corresponding field at the top of the widget's frame. A drop-down menu with all your campaigns appears, allowing you to select the campaign by which you want your widget filtered.
Please keep in mind that there are several filters to choose from that can be applied to the corresponding widgets. Furthermore, you can always export the data of each widget in order to have them at your disposal at all times.