how do i get the heatercore out?

This is a tough job. You need to partially remove the dash to get access to the heater core. It's a job for an experienced machanic. I recommmend a Ford specialist or someone with Escort experience. If you feel you really want to take on this job, there are online manuals you can access from AutoZone if you register online, or you could probably find a manual at the public library. Here's a directory link for you: http://repairpal.com/ford-repair-in-crookston-minnesota