What the best way to convert a sample data file into a datagen?

Hover your mouse over the sample file you wish to use in a datagen, and a pencil icon will appear near the name of that sample file. Clicking on the pencil icon will bring up the edit dialog box for that sample file. You can click the "Create Datagen from Sample" button within the edit dialog box to create the datagen file. After you have followed the process to create the datagen file, you will be able to choose that file from within the datagen source.