I found this little article at crosswalk, by pastor Roger Barrier, who writes a weekly column, Ask Roger at Preach It, Teach It. I related to it, for I have not been well-trained regarding fasting either. Though fasting is not commanded in the New Testament, it is a practice that can bring us closer to God. Following, are verse and quotes from Why Should I Fast?, by Roger Barrier, founder of Preach It, Teach It. You can read the entire article here, at crosswalk.com
Reader, Lacy, asks this question, "Why isn't fasting emphasized in the church today? What does not eating have to do with spirituality? Why should I fast? What does a fast look like?"
Roger responds, "Nowhere in the New Testament are we commanded to fast. On the other hand, Jesus assumes that there will be times when His followers will practice fasting.
"One of my pastor friends, Jeff Jones, gave the best definition for fasting that I have ever heard: "Fasting is a voluntary choice not to eat for a period of time in order to focus one’s attention on prayer during a significant moment in life."
14 Then the disciples of John came to Him, asking, "Why do we and the Pharisees fast, but Your disciples do not fast?"
15 And Jesus said to them, "The attendants of the bridegroom cannot mourn as long as the bridegroom is with them, can they? But the days will come when the bridegroom is taken away from them, and then they will fast.
I hope you can read the entire article, and explore Preach It, Teach It a bit. There is much to learn there. You may find some of your favorite pastors and ministers as well.