Importing large number of shapefiles into feature class using ArcPy with column mapping?

I'd like to write an ArcPy script to import a large number of shapefiles into an EXISTING feature class. I also need to be able to perform column mappings as there may be different column names. I need to write a script so I can automate this process.

I'm not looking for a complete script but rather advice as to where I should be looking to perform this task. I'm fairly new to ArcGIS.