Simply replace the unfilled areas such as "" and "[date]" with your information.
As you know, I have been with [name of company] for some time now and feel that I have contributed much to the ongoing success of this organization. [name of company] has treated me well over the years and I have really enjoyed working here. However, I do feel the need for new challenges.
I want to personally make you aware of what I have set my sights on with [name of company]. It is my ambition to [briefly describe what your ultimate goal is. don't tell your boss you want her job.]. With my existing experience and education, my willingness to learn and my strong desire to take on new challenges, I believe that I have what it takes to succeed.
With this in mind, I think I would be a great candidate for a new [type] opening in one of our branches/the new [type position that recently became available/etc.]. I am convinced that I could do a good job for [name of organization] as a [type of position]. My total commitment would be focused on [making that branch even more successful/increasing productivity/etc.]. You can count on me to put everything i got into my work and I wouldn't let you down.
Thank you for taking the time to consider me for [the type position/the next time a [type] position becomes available/etc].