Sounds like you need to place a "Buy" order. When you first open your account the money goes in as a deposit but then you need to tell them where to put it, which is done by buying shares in a fund.
You can find the Buy feature by clicking on your account and then options will show up at the top of the account. Look for the 'Buy and Sell' link and click on it. There you will purchase the funds you desire. If you have any trouble at all just call Vanguard assistance for help. They are wonderful and very helpful.