To download a product, go to your purchases page, and browse through your purchased bundles for the product you want. If you know the title of what you want to download, click on the appropriate tab for the type of product (Games/Music/Other product) and use the search field to quickly locate the product.
Once you've located the product, click on its "Download" button. You will be presented with the operating systems (in case of games) and formats (for everything else) the product can be downloaded in. In each OS/format, there are links to download directly.
Please note that for new purchases, you must reveal the product before you can download its files. Revealing a product will prevent you from being able to trade or gift the product and its parent bundle.