The URL tracker is found under your account under "URL tracker". The affiliate codes (if they've already been entered into your account) can be found under "Affiliate Settings" (in "account").
In order to get up and running with affiliates you have to first apply and get approved (it can take a couple of days or longer). Once you're approved you'll be notified. From there you'll either see exactly what your code if (I don't recall the exact steps); or else you'll be able to go to your account with each, individual, affiliate; and find your affiliate code.
From there, you would copy the code and paste it into your HubPages account (unless it's already in there).