Site definition dialogue.
At the top of this dialogue box there are two tabs, choose the Advanced tab and then choose the remote info category from the category list on the left of the panel.
HOSTIT4U
Above you can see the settings for hostit4u.co.uk.
Replace 'yoursite' with your subdomain name that you chose when registering, input your username and password that was included in the 'ftp details' you received in the activation email from your hosting provider.