Unfortunately, rejection is a part of writing no matter how experienced or inexperienced the author. All writers have their work rejected at one time or another.
Rarely, do publishers offer feedback on your work. Most rejections come as a form letter telling you that your manuscript does not meet their present needs. While you will feel disappointed, it is important to remember that it is not you being rejected and you should not take it personally. Most writers immediately feel as if their work was rejected because it was not good enough. This is not necessarily the case. Many times manuscripts are rejected because they do not fit the guidelines of the publishers, or other similar pieces have already been submitted.
Good writing takes time and for most authors it is a work in progress. If a piece is rejected, go through it carefully and determine whether there are areas that could be improved upon.
Don’t give up when you receive a rejection slip. Pack up the manuscript and send it off to another publisher until you find one whose needs it fits. Many famous authors have had well-known manuscripts rejected. Develop a thick skin, be persistent, and with patience there will come a day that you get those acceptance letters every author dreams of getting.