How to create a log file in Web Api 2?

i need create log file info each api called (user, ip, api, timestamp, etc.).

i read articles, best are:

1. http://www.asp.net/web-api/overview/testing-and-debugging/tracing-in-aspnet-web-api
2. http://arcware.net/logging-web-api-requests/

but can’t understand how utilize within app. tutorials or guides appreciated.