There are two ways of making monry from docstoc; from selling your documents and from integrating adsense to your documents
Selling your Documents:
Like I said earlier, you can upload your documents and fix a price for the document. If anybody is interested in the document, he/she will pay to download the document. and the proceed from the sale shared between you and docstoc on a 50:50 basis.
Integrating Google Adsense
Google adsense is a program where search engine giants, google places an advert related to your document beside your document. And you will be paid once anybody clicks on the advert. It is called Doccash. If you do not have a google adsense account, do not worry docstoc will help you get one.
NB: Docstoc reviews all the documents you upload to see if they are original and that can take quite some time. So make sure you upload just documentswith original content.
To start visit www.docstoc.com