How to create a log file ? VB.Net Code Visual Basic software program for beginners

       A log file in programming is very important especially during trial/testing period of a software development  because the log file in any programming language or Visual Basic  can be used to catch the error which were generated while using the software and get it solved while debugging. For better understanding of these type of vb.net code or database related inquiry the book written by Mike Murach is very good book which is available on amazon with free shipping charge, I will suggest one can  refer.So a log files help a programmer  lots as it gives details about actual error, otherwise you have to depend upon the user who is using the