If you have a gmail account, then you already have access to Google Docs. Just log in to your e-mail account and click on the Documents link at the top of the page.
If you do not have a gmail account, you can get one by going to mail.google.com.
If you prefer not to use gmail, you can still get a Google account by following the steps in this video.
Once you have established a Google account you have access to a number of utilities. Google Docs allows you to either upload a paper to your Google account or compose it online. Google automatically saves your paper and it allows you to share it with anyone else who has a Google account.
To submit an assignment using Google Docs proceed as follows.
Alternatively, at step 3 you may upload a document by clicking on Upload. If you do this be sure to re-title your essay according to step 4 and follow the rest of the steps. Also, be sure to examine the uploaded document to be sure the formatting has been preserved.
When you complete step 11, I will have a copy of the essay in my Google account.
Here are a couple of other videos explaining how Google Docs works.