How to create log file for ETL operation ?

Hello,

I have created a sample project for ETL operation. For that 

1. Source - Flat file is the source from which data are extract. It contains ID,Name and Address Columns

2. Transformation - Lookup that check for duplicate Name in SQL Server table e.g Employee which contain all the three                                       columns.

I would like to write Look up match rows in log file. 

How can I achieve this?

Thanks in advance.