In the app navigate to the robot by selecting the team the robot is in from the navigation menu and then selecting Robots.
Select the robot you want to use from the list of robots, if you only have a single robot there will only be one to select.
In the lower right select the blue icon with the plus sign to add a new part
Enter a distinctive name for the part and a description, press next
Enter your default weld settings, these will be the settings that are applied to points as you are teaching new weld segments.