When you have access to two or more accounts, you can easily switch between accounts with the button "Switch Accounts". You can find this button on the upper right side. Once you click the button, it will show you all the accounts you have access to.
When you click on the "Switch Accounts" button, you will see a list similar to the one shown below. This will contain all the accounts you have access to. If you don't see your account in the "Recents" list, you can find it by typing its name into the search bar.
Once you click over an account name, you will be redirected to that account in the Web.
Check out the following video to see this in action.