To view additional details beyond current dollar value and quantity of individual holdings in your portfolio, simply scroll down to the holdings section on your portfolio page and tap or click on any of the assets you hold.
At the very top of asset details - you should see the latest available price of the asset.
All trade-able assets should have a historical price chart as well as other details such as quantity held, dollar value of holdings, performance over time, an estimate of taxes saved and a full trade history.
Each trade also has a sub-screen that carries the individual details of that trade if you ever need them. You can also cancel pending orders for an asset from this screen, if you have any pending trades.
If an asset is trade-able - you will also see Buy and Sell buttons appear for this asset - at the top right if you are on larger format screens, and at the bottom of the window if you are smaller format screens.