When opening the software, you will immediately find a window which will allow you to check documents for compatibility with the PDF/A standard of your choice. Just drag-and-drop your file(s) on the pdfaPilot window (1), and click on the "Check for PDF/A..." button (2).
After the check is performed, you are able to see if your document is PDF/A-valid or not (1). If not, a list of the problems will be given (2) why it is not compatible with the PDF/A standard of your choice.
By clicking on the "Convert to PDF/A..." button on the bottom of the pallet, you can convert the current document to a valid PDF/A document.
You will be prompted with a window to save your PDF/A.
Once the document is converted and saved, you will receive a confirmation about the successful conversion to PDF/A.
In the preferences you can specify what the default PDF/A format should be to check for or to convert to. This will make your life even easier not to having to set this for every document you process. The manual will give you an overview of what options are checked for which version of the PDF/A you want to use.