A "Simple" portfolio is useful for users who don't wish to all of the past historical transactions to their portfolios. A "simple" portfolio lets you track holdings by only entering a ticker symbol and the number of shares currently owned.
To create a simple portfolio, create a portfolio and check the "This is a simple portfolio" box. Then, for each stock owned, enter the ticker symbol and number of shares of each.
Going forward, you will need to manually update the number of shares for each Simple Portfolio whenever you buy or sell stocks from that portfolio. You will have access to all fundamental reports -- such as the diversification and equity reports -- but the gain/loss and performance reports won't be valid or available (since the cost basis isn't available for the holdings).