You can easily add documents stored on your computer to your Interfolio account. You'll need to create a placeholder for the document, which you can do from your My Documents screen.

Once there, simply click the link to “Add Document.” You'll then need to choose a document type, give a unique title to your document, and choose how to get the document into your account.

Since the document is already on your computer, choose the option that reads “Electronic document - You have an electronic file that you are able to upload now.” Find the document on your computer, and then upload it. The document may take a few minutes to convert, so don't worry of the status is “Converting” for several minutes.