You can either include content alongside name and asset_type when you make your first POST or update it later with a PATCH. Try making a new project and adding a few questions using the form builder, and then visit the asset detail URL (https://kobo.humanitarianresponse.info/assets/<your-asset-uid>/?format=json). You should see your questions in the content object, which contains survey, choices, and settings—these should look familiar if you know XLSForm.
Alternatively, you could import XLSForm directly using the API as described in KoBo API examples, using new KPI endpoints.
