To start, make sure you have added a TPC Form Layout to your form, with a TPC Form Configuration widget added and configured to an entity.
Then, drag and drop the Sub-List View widget from The Portal Connector tools into the body of your form, then click Edit to configure Sub-List View properties.
The Basic tab contains a number of options allowing you to determine user abilities for adding, editing and deleting records.
The data tab is used for defining FetchXML, which will determine what records the Sub-List View will display. The Sub-List View inherits the configured entity from the Form Configuration widget, and the following options are used to determine what related data will be included.
Records - Select Only Related Records (to the configured entity) or All Record Types.
Build - Opens the TPC FetchXML builder. Add attributes that you want to display, as well as Linked-Entities and Filters. For more information, see the How To's section at the bottom of this page.
The Filters option allows you to filter the data that is retrieved for the grid.
The Columns tab provides options to Add Column, edit the Column Type, Name, or Header, or even Format HTML for the column. For example, a column displaying email addresses could be formatted as clickable mailto: links.
Advanced properties provide additional functionality. They can be accessed by clicking on the "Advanced" Button in the bottom right corner of the widget designer.