First, you need to login to webmail like you did before. Right click this link and open it in a new window. That way you can go back and forth between the webmail and these instructions.
Now you need to tell SpamCop to POP your mail from your old account for you. SpamCop will periodically poll the old server, grab any new mail, and filter it. In the webmail program, first click Options at the top, then SpamCop Tools. This is where you set up all SpamCop options and here you should click Configure external POP servers.
This form has lines to insert several POP servers, if you have several email addresses that you need to POP. The first three fields are the items you wrote down earlier. Do not click "Leave on server" as this can cause problems. AT&T Broadband customers (attbi.com) should click "Use SSL" and nobody else should. When you have entered your info, click Modify at the bottom. Remember, all this info is your old account.
At this point, you're ready to proceed to Step 2. It can take up to an hour for POP to start working, so don't worry if this doesn't seem to work immediately.