Click on the iPhone Trader icon logo and you will come to a login page for your trading account.
Click on the text fields to edit and input your login and password:
Login - Your trading account login
Password - Your trading account password
Servers - By clicking on the 'Server' button, you have the option of selecting the server.
After entering your account login details, click on the 'Login' button.
Once clicking on the login button, your iPhone will attempt to connect to the server and log you into your trading account.