There are several ways to provide audio comments to papers so that you can upload those comments to moodle or email them to students. I've found audio comments to be ideal for providing responses to early drafts, when students are still playing with ideas and looking for a focus for their work.
I begin by asking them to either upload their papers to Moodle or email them to me as word doc attachments. I then open and save those documents to my own computer as either pdf files or as word documents.
If you have Adobe Acrobat, click here to see how to record in a pdf document.
If you don't have Adobe Acrobat, click here to see how to record in a word document.