We are using log4net in our project. It works great. Here are some links and tips to get you started.
In this tutorial on codeproject you can read all the details and even see a video about it. Very good starting point for getting to know log4net.
We plan to use MEF for IoC. In Little Trick to generate ILogger with MEF based on type you can read how to get it to work. It involves a wrapper around the log4net.ILog interface and an implementation that creates the log4net logger and redirects the calls to log4net.
As last a reference to the Log4net Layout Patternlayout documentation. With the PatternLayout you can configure the information in the output.
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.NET Development by Eric 