To access The Washington Post's daily paper online, go to: www.washingtonpost.com/todays_paper.
Alternatively, you can go to Washington Post's homepage and click on the link.
Once you get to Today's Paper, you should see something like this:
What's cool about The Washington Post is that it shows you the entire front page (and other pages). You can then click on the actual article to read it. This way, you, as the reader, can see what the paper deemed to be the most important stories on that day.
Like The New York Times, you can also access up to one week's worth of past front pages. This way, if you didn't get a chance to read the paper on a particular day, you can always catch up.