Log4net is saving into your project folder. Something like: \SolutionFolder\ProjectFolder\bin\SolutionConfiguration\logs\log-file.txt
.
Where:
- SolutionFolder is where you save your solution
- ProjectFolder is the folder where your project lives into the solution and
- SolutionConfiguration is the folder that contais all the binaries of your project (the default is Debug or Release)
Hope this helps!